Fix style issues from docs review

- Fix version phrasing in overlay: "v26.1 and later" -> "version 26.1 or later"
- Fix comma splice in schema_metadata_request description
- Add missing description to defaultToGlobal on GET /config/{subject}
- Clarify "subject-version" -> "subject-version pairs" in summary
- Make POST /security/acls description add value beyond the summary

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: kbatuigas

schema-registry/overlays/add-external-docs.yaml

@@ -16,4 +16,4 @@ actions:
         - [Use Redpanda Cloud with the Schema Registry API](https://docs.redpanda.com/redpanda-cloud/manage/schema-reg/schema-reg-api/)
         - [Use Redpanda Self-Managed with the Schema Registry API](https://docs.redpanda.com/current/manage/schema-reg/schema-reg-api/)
         
-        Schema Registry contexts (available in Redpanda v26.1 and later) provide an isolated namespace for schemas, subjects, and configuration. Any endpoint path can be prefixed with `/contexts/{context}/` to scope operations to a specific context, and you can also use a context-qualified subject anywhere the API accepts a subject. See the [Redpanda Cloud](https://docs.redpanda.com/redpanda-cloud/manage/schema-reg/schema-reg-contexts/) (configurable only in BYOC and Dedicated clusters) or [Redpanda Self-Managed](https://docs.redpanda.com/current/manage/schema-reg/schema-reg-contexts/) documentation for details.
+        Schema Registry contexts (available in Redpanda version 26.1 or later) provide an isolated namespace for schemas, subjects, and configuration. Any endpoint path can be prefixed with `/contexts/{context}/` to scope operations to a specific context, and you can also use a context-qualified subject anywhere the API accepts a subject. See the [Redpanda Cloud](https://docs.redpanda.com/redpanda-cloud/manage/schema-reg/schema-reg-contexts/) (configurable only in BYOC and Dedicated clusters) or [Redpanda Self-Managed](https://docs.redpanda.com/current/manage/schema-reg/schema-reg-contexts/) documentation for details.

schema-registry/schema-registry.json

@@ -24,6 +24,7 @@
           },
           {
             "name": "defaultToGlobal",
+            "description": "If true, return the global compatibility level if the subject doesn't have a level set.",
             "in": "query",
             "required": false,
             "type": "boolean"
@@ -570,7 +571,7 @@
     },
     "/schemas/ids/{id}/versions": {
       "get": {
-        "summary": "Get a list of subject-version for the schema ID.",
+        "summary": "Get a list of subject-version pairs for the schema ID.",
         "operationId": "get_schemas_ids_id_versions",
         "parameters": [
           {
@@ -1545,7 +1546,7 @@
       },
       "post": {
         "summary": "Create ACLs",
-        "description": "Create new ACL rules.",
+        "description": "Create one or more ACL rules. The request body is an array of ACL definitions.",
         "operationId": "post_security_acls",
         "parameters": [
           {
@@ -1689,7 +1690,7 @@
       "properties": {
         "properties": {
           "type": "object",
-          "description": "Accepted values may be string, number, or boolean, they are converted to strings.",
+          "description": "Accepted values may be string, number, or boolean. All values are converted to strings.",
           "additionalProperties": {
             "type": "string"
           }