DOC-1337 Notice about large schemas (#1274)

Author: Feediver1

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

@@ -6,11 +6,16 @@
 
 In Redpanda, the messages exchanged between producers and consumers contain raw bytes. Schemas enable producers and consumers to share the information needed to serialize and deserialize those messages. They register and retrieve the schemas they use in the Schema Registry to ensure data verification.
 
-Schemas are versioned, and the registry supports configurable compatibility modes between schema versions. When a producer or a consumer requests to register a schema change, the registry checks for schema compatibility and returns an error for an incompatible change. Compatibility modes can ensure that data flowing through a system is well-structured and easily evolves. 
+Schemas are versioned, and the registry supports configurable compatibility modes between schema versions. When a producer or a consumer requests to register a schema change, the registry checks for schema compatibility and returns an error for an incompatible change. Compatibility modes can ensure that data flowing through a system is well-structured and easily evolves.
+
+[IMPORTANT]
+====
+*Schema size best practice*: Schema Registry works best with schemas of 128KB in size or less. Large schemas can consume significant memory resources and may cause system instability or crashes, particularly in memory-constrained environments. For Protobuf and Avro schemas, Redpanda recommends using schema xref:manage:schema-reg/schema-reg-api.adoc#reference-a-schema[references] to break up large schemas into smaller constituent parts.
+====
 
 [NOTE]
 ====
-The Schema Registry is built directly into the Redpanda binary. It runs out of the box with Redpanda's default configuration, and it requires no new binaries to install and no new services to deploy or maintain. You can use it with the xref:manage:schema-reg/schema-reg-api.adoc[Schema Registry API] or xref:manage:schema-reg/schema-reg-ui.adoc[{ui}]. 
+The Schema Registry is built directly into the Redpanda binary. It runs out of the box with Redpanda's default configuration, and it requires no new binaries to install and no new services to deploy or maintain. You can use it with the xref:manage:schema-reg/schema-reg-api.adoc[Schema Registry API] or xref:manage:schema-reg/schema-reg-ui.adoc[{ui}].
 ====
 
 == Schema terminology