DOC-1265 Make _schema topic modification unsupported (#1142)

Author: Feediver1

modules/manage/pages/schema-reg/schema-reg-overview.adoc

@@ -27,11 +27,14 @@ The Schema Registry is built directly into the Redpanda binary. It runs out of t
 
 Every broker allows mutating REST calls, so there's no need to configure leadership or failover strategies. Schemas are stored in a compacted topic, and the registry uses optimistic concurrency control at the topic level to detect and avoid collisions.
 
-The Schema Registry publishes record metadata to an internal topic, `_schemas`, as its backend store. By default, `_schemas` is protected from deletion and configuration changes by Kafka clients.
+[IMPORTANT]
+====
+The Schema Registry publishes an internal topic, `_schemas`, as its backend store. This internal topic is reserved strictly for schema metadata and support purposes. *Do not directly edit or manipulate the `_schemas` topic unless directed to do so by Redpanda Support.*
 ifndef::env-cloud[]
 See the xref:reference:cluster-properties.adoc#kafka_nodelete_topics[kafka_nodelete_topics] cluster property.
 
 endif::[]
+====
 
 Redpanda Schema Registry uses the default port 8081.