Mention the supported Kafka version in the docs

Running older versions than this may work, but we don't test for it, and
we may have to break compat in the future. Write a policy down!

Author: bkirwi

doc/user/content/ingest-data/kafka/_index.md

@@ -15,6 +15,10 @@ from Kafka, you need to
 1. Create a connection that specifies access and authentication parameters.
 2. Create a source that specifies the format of the data you want to ingest.
 
+## Supported versions
+
+The Kafka source supports **Kafka 3.2+** and is compatible with most common Kafka hosted services, including all supported versions of the [Confluent Platform](https://docs.confluent.io/platform/current/installation/versions-interoperability.html).
+
 ## Integration guides
 
 - [Amazon MSK](/ingest-data/kafka/amazon-msk/)

doc/user/content/ingest-data/kafka/kafka-self-hosted.md

@@ -27,7 +27,7 @@ self-hosted Kafka cluster.
 
 Before you begin, you must have:
 
-- A Kafka cluster running.
+- A Kafka cluster running Kafka 3.2 or later.
 - A client machine that can interact with your cluster.
 
 ## Configure network security

doc/user/content/ingest-data/redpanda/_index.md

@@ -36,6 +36,10 @@ enabled explicitly in Redpanda:
 For more information on general Redpanda configuration, see the
 [Redpanda documentation](https://docs.redpanda.com/home/).
 
+## Supported versions
+
+Materialize supports **Redpanda 24.1+** and is compatible with most common Redpanda hosted services. This includes [all officially supported versions of Redpanda](https://support.redpanda.com/hc/en-us/articles/20617574366743-Redpanda-Supported-Versions).
+
 ## Related pages
 
 - [`CREATE SOURCE`](/sql/create-source/kafka/)