ECE: Disabling CPU hard limit and podman limitation (#1511)

This PR introduces the CPU hard limit configuration (enable / disable)
within the `Resource overrides` page, and it describes that it doesn't
have any effect on Podman hosts.

I have also refined the introduction of the page.

Preview:
- [Resource
Overrides](https://docs-v3-preview.elastic.dev/elastic/docs-content/pull/1511/deploy-manage/deploy/cloud-enterprise/resource-overrides)

The reason of adding this is:

- This is available in ECE UI for all users and we didn't have it
documented anywhere (thanks @frconil for pointing this out). So there's
no point of `hiding` this button of the UI.
- We have some public KB articles that also mention this setting (CPU
hard limit toggling).
- We now want to introduce a banner saying that this doesn't work in
Podman, but we didn't have this even documented at all.

I have added some warnings and implications of using this setting, and
recommending to do it only when being guided by Support.

This PR will also be aligned with
#1418 for the Podman
limitation.

---------

Co-authored-by: shainaraskas <[email protected]>

Author: eedugon

deploy-manage/deploy/cloud-enterprise/resource-overrides.md

@@ -10,7 +10,9 @@ products:
 
 # Resource overrides [ece-resource-overrides]
 
-{{ecloud}} allocators assign resources to {{es}} instances based on RAM, where RAM is proportional to CPU and disk resources. As needed, you can temporarily override the allocated resources to stabilize the deployment. You should reset overrides as soon as possible, or make the override permanent by [changing your configuration](working-with-deployments.md).
+{{ecloud}} allocators assign resources to {{es}} instances based on RAM, where RAM is proportional to CPU and disk resources. As needed, you can temporarily override the allocated resources to stabilize the deployment. To do this, use the contextual menu available on each instance in the deployment UI.
+
+Overrides are intended to be temporary and may be lost after making configuration changes to the deployment. You should reset overrides as soon as possible, or make them permanent by [changing your configuration](./configure-deployment.md).
 
 The RAM to CPU proportions can’t be overridden per instance.
 
@@ -31,3 +33,35 @@ Overriding the instance size restarts the {{es}} node.
 ::::
 
 When an instance within a deployment has resource overrides, it displays a warning banner reading **Elastic added temporary capacity to stabilize the deployment**. [Configuration changes](working-with-deployments.md) can still be safely submitted.
+
+## Disabling CPU quotas at deployment level [cpu-hard-limit]
+
+In addition to overriding resources for individual instances, you can also completely disable CPU limits for your deployment from the **Operations** page of each deployment.
+
+::::{note}
+When running ECE on Podman, CPU quotas for existing instances cannot be removed or updated. As a result, disabling the CPU hard limit has no effect on Podman-based allocators.
+::::
+
+::::{important}
+Disabling the CPU hard limit for an entire deployment is an advanced action and should be approached with caution. This setting removes CPU quotas from the containers, which means some instances could consume excessive CPU resources and degrade the performance of other instances running on the same allocators.
+
+We strongly recommend making this change only under the guidance of Elastic Support, and only as a temporary measure or for troubleshooting purposes.
+::::
+
+To disable CPU limits of your deployment instances, choose one of the following methods:
+
+* Open the **Operations** page of the deployment UI, and select **Turn off** in the **CPU hard limit** section.
+
+* Use the [advanced editor](./advanced-cluster-configuration.md), and in the **{{es}} cluster data** section, look for the following setting:
+
+  ```yaml
+        "resources": {
+          "cpu": {
+            "hard_limit": false
+          }
+        }
+  ```
+
+  Set `hard_limit` to `false` to disable CPU limits, or to `true` to enforce strict CPU limits (default behavior).
+
+This change doesn’t require a restart of the deployment.