[ECE] Clarify supported Ubuntu version (#1621)

(This is the 2nd try of previously wrongly raised PR -
#1620)

## Description

Previously we specify Ubuntu (Operating system / OS) version directly
like 20.04 or 22.04.
However, we later also 24.04, and maybe in the future we will have even
more versions.

All the compatible and supported version could be found in our support
matrix - https://www.elastic.co/support/matrix#elastic-cloud-enterprise.

But writing the version directly to public doc page other than support
matrix seems to be easily forgotten to update, and thus we are left
behind in public doc page that it does not mention 24.04 now.
=> This causes confusion on users, because it's telling different in
between public ECE docs and support matrix.

This was brought up by @rheppe in an internal discussion
[here](https://elastic.slack.com/archives/C045W6699NH/p1748919036870519?thread_ts=1748559251.195289&cid=C045W6699NH).

The rationale is that support matrix is the source of truth, per what we
have confirmed with @Kushmaro. So we would like to update the public
docs based on support matrix.

## Additional Notes

- We removed note `Docker 25 and higher are not compatible with ECE
3.7.` because the current branch of docs is for ECE 4.0, and we can see
from support matrix, it's supported.
- We also explicitly mentioned that, the command mentioned in `sudo apt
install -y docker-ce=5:24.0.* docker-ce-cli=5:24.0.* containerd.io` is
just an example of install Docker 24.0 on Ubuntu. We added this because
per support matrix, ECE 4.0 also supports other docker versions, and we
can see from the screenshots below, it's hard to make an exclusive list
in the public doc page, thus it makes more logical sense to say "it's a
command example".

<img width="1728" alt="image"
src="https://github.com/user-attachments/assets/ca2f0c00-427c-46cf-b2fe-05e69a527e90"
/>


## Before / After PR merge

### Before

<img width="1225" alt="image"
src="https://github.com/user-attachments/assets/94ff5f0d-136d-4382-935c-0bba1252ef6d"
/>


### After

No 20.04 or 22.04 version number present

<img width="1359" alt="image"
src="https://github.com/user-attachments/assets/76ad92e3-a439-467a-8f19-75547c8910ba"
/>

---------

Co-authored-by: Edu González de la Herrán <[email protected]>

Author: kunisen

deploy-manage/deploy/cloud-enterprise/configure-host-rhel.md

@@ -12,13 +12,10 @@ products:
 
 # Configure a RHEL host [ece-configure-hosts-rhel-centos]
 
-
-
 The following instructions show you how to prepare your hosts on Red Hat Enterprise Linux 8 (RHEL 8), 9 (RHEL 9), and Rocky Linux 8 and 9.
 
 * [Prerequisites](#ece-prerequisites-rhel8)
-* [Configure the host](#ece-configure-hosts-rhel8-podman)
-
+* [Install Podman and configure the host](#ece-configure-hosts-rhel8-podman)
 
 ## Prerequisites [ece-prerequisites-rhel8]
 
@@ -28,7 +25,11 @@ Verify that required traffic is allowed. Check the [Networking prerequisites](ec
 
 **Example:** For AWS, allowing traffic between hosts is implemented using security groups.
 
-## Configure the host [ece-configure-hosts-rhel8-podman]
+::::{important}
+Make sure to use a supported combination of Linux distribution and container engine version as defined in our official [Support matrix](https://www.elastic.co/support/matrix#elastic-cloud-enterprise). Unsupported combinations can lead to various issues in your ECE environment, including failures when creating system deployments, upgrading workload deployments, proxy timeouts, and more.
+::::
+
+## Install Podman and configure the host [ece-configure-hosts-rhel8-podman]
 
 1. Install the OS packages `lvm2`, `iptables`, `sysstat`, and `net-tools` by executing:
 

deploy-manage/deploy/cloud-enterprise/configure-host-suse.md

@@ -12,10 +12,10 @@ products:
 
 # Configure a SUSE host [ece-configure-hosts-sles12]
 
-The following instructions show you how to prepare your hosts on SLES 12 SP5 or 15.
+The following instructions explain how to prepare your hosts on SUSE Linux Enterprise Server 12 SP5 (SLES 12) or 15 (SLES 15).
 
 * [Install Docker](#ece-install-docker-sles12)
-* [Set up XFS on SLES](#ece-xfs-setup-sles12)
+* [Set up XFS quotas](#ece-xfs-setup-sles12)
 * [Update the configurations settings](#ece-update-config-sles)
 * [Configure the Docker daemon options](#ece-configure-docker-daemon-sles12)
 
@@ -26,11 +26,10 @@ If you want to install {{ece}} (ECE) on your own hosts, the steps for preparing
 
 Regardless of which approach you take, the steps in this section need to be performed on every host that you want to use with ECE.
 
-
-## Install Docker [ece-install-docker-sles12]
+## Install Docker on SLES [ece-install-docker-sles12]
 
 ::::{important}
-Make sure to use a combination of Linux distribution and Docker version that is supported, following our official [Support matrix](https://www.elastic.co/support/matrix#elastic-cloud-enterprise). Using unsupported combinations can cause multiple issues with you ECE environment, such as failures to create system deployments, to upgrade workload deployments, proxy timeouts, and more.
+Make sure to use a supported combination of Linux distribution and container engine version as defined in our official [Support matrix](https://www.elastic.co/support/matrix#elastic-cloud-enterprise). Unsupported combinations can lead to various issues in your ECE environment, including failures when creating system deployments, upgrading workload deployments, proxy timeouts, and more.
 ::::
 
 
@@ -87,7 +86,7 @@ Make sure to use a combination of Linux distribution and Docker version that is
 
 
 
-## Set up XFS on SLES [ece-xfs-setup-sles12]
+## Set up XFS quotas [ece-xfs-setup-sles12]
 
 XFS is required to support disk space quotas for {{es}} data directories. Some Linux distributions such as RHEL and Rocky Linux already provide XFS as the default file system. On SLES 12 and 15, you need to set up an XFS file system and have quotas enabled.
 

deploy-manage/deploy/cloud-enterprise/configure-host-ubuntu.md

@@ -12,25 +12,20 @@ products:
 
 # Configure an Ubuntu host [ece-configure-hosts-ubuntu]
 
-The following instructions show you how to prepare your hosts on 20.04 LTS (Focal Fossa) and Ubuntu 22.04 LTS (Jammy Jellyfish).
+The following instructions show you how to prepare your hosts on Ubuntu.
 
-* [Install Docker 24.0](#ece-install-docker-ubuntu)
+* [Install Docker](#ece-install-docker-ubuntu)
 * [Set up XFS quotas](#ece-xfs-setup-ubuntu)
 * [Update the configurations settings](#ece-update-config-ubuntu)
 * [Configure the Docker daemon options](#ece-configure-docker-daemon-ubuntu)
 
 
-## Install Docker [ece-install-docker-ubuntu]
+## Install Docker on Ubuntu [ece-install-docker-ubuntu]
 
-Install Docker LTS version 24.0 for Ubuntu 20.04 or 22.04.
+Install a compatible Docker version on Ubuntu.
 
 ::::{important}
-Make sure to use a combination of Linux distribution and Docker version that is supported, following our official [Support matrix](https://www.elastic.co/support/matrix#elastic-cloud-enterprise). Using unsupported combinations can cause multiple issues with you ECE environment, such as failures to create system deployments, to upgrade workload deployments, proxy timeouts, and more.
-::::
-
-
-::::{note}
-Docker 25 and higher are not compatible with ECE 3.7.
+Make sure to use a supported combination of Linux distribution and container engine version as defined in our official [Support matrix](https://www.elastic.co/support/matrix#elastic-cloud-enterprise). Unsupported combinations can lead to various issues in your ECE environment, including failures when creating system deployments, upgrading workload deployments, proxy timeouts, and more.
 ::::
 
 
@@ -55,10 +50,10 @@ Docker 25 and higher are not compatible with ECE 3.7.
       $(lsb_release -cs) stable" | sudo tee /etc/apt/sources.list.d/docker.list > /dev/null
     ```
 
-4. Install the correct version of the `docker-ce` package, for Ubuntu 20.04 LTS (Focal Fossa) or Ubuntu 22.04 LTS (Jammy Jellyfish):
+4. Install the correct version of the `docker-ce` package. The following is an example of installing Docker 27.0. If you decide to install a different Docker version, make sure to replace with the desired version in the commands below.
 
     ```sh
-    sudo apt install -y docker-ce=5:24.0.* docker-ce-cli=5:24.0.* containerd.io
+    sudo apt install -y docker-ce=5:27.0.* docker-ce-cli=5:27.0.* containerd.io
     ```
 
 

deploy-manage/deploy/cloud-enterprise/configure-operating-system.md

@@ -13,7 +13,10 @@ products:
 
 Before installing {{ece}}, you have to prepare your hosts with one of the following Linux distributions:
 
-* [Ubuntu 20.04 LTS (Focal Fossa) and Ubuntu 22.04 LTS (Jammy Jellyfish)](configure-host-ubuntu.md)
-* [Red Hat Enterprise Linux (RHEL) 8 and 9](configure-host-rhel.md)
-* [Rocky Linux 8 and 9](configure-host-rhel.md)
-* [SUSE Linux Enterprise Server (SLES) 12 SP5 and 15](configure-host-suse.md)
+* [Ubuntu](configure-host-ubuntu.md)
+* [Red Hat Enterprise Linux (RHEL) and Rocky Linux](configure-host-rhel.md)
+* [SUSE Linux Enterprise Server (SLES)](configure-host-suse.md)
+
+::::{important}
+Make sure to use a supported combination of Linux distribution and container engine version, such as `Docker` or `Podman`, as defined in our official [Support matrix](https://www.elastic.co/support/matrix#elastic-cloud-enterprise). Unsupported combinations can lead to various issues in your ECE environment, including failures when creating system deployments, upgrading workload deployments, proxy timeouts, and more.
+::::