docs: document x-circular-ref support

Author: sserrata

demo/docs/intro.mdx

@@ -69,7 +69,7 @@ The plugin extracts a number of vendor extensions from the OpenAPI spec to enric
 | `x-displayName`                            | Overrides tag display names. |
 | `x-enumDescription` / `x-enumDescriptions` | Documents enum values. |
 
-Other ReDoc specific extensions such as `x-circular-ref`, `x-code-samples` (deprecated), `x-examples`, `x-ignoredHeaderParameters`, `x-nullable`, `x-servers`, `x-traitTag`, `x-additionalPropertiesName`, and `x-explicitMappingOnly` are ignored when extracting custom data.
+Circular references flagged with `x-circular-ref` or detected automatically are serialized as `circular(<title>)`. Other ReDoc specific extensions such as `x-code-samples` (deprecated), `x-examples`, `x-ignoredHeaderParameters`, `x-nullable`, `x-servers`, `x-traitTag`, `x-additionalPropertiesName`, and `x-explicitMappingOnly` are ignored when extracting custom data.
 
 ---
 

demo/docs/vendor-extensions.mdx

@@ -21,4 +21,4 @@ The OpenAPI plugin and theme recognize several [vendor extensions](https://swagg
 | `x-displayName` | Override tag names used for grouping. |
 | `x-enumDescription` / `x-enumDescriptions` | Document individual enum values. |
 
-Other ReDoc extensions such as `x-circular-ref`, `x-code-samples` (deprecated), `x-examples`, `x-ignoredHeaderParameters`, `x-nullable`, `x-servers`, `x-traitTag`, `x-additionalPropertiesName`, and `x-explicitMappingOnly` are detected but ignored when extracting custom extensions.
+Circular references flagged with `x-circular-ref` or detected automatically are serialized as `circular(<title>)`. Other ReDoc extensions such as `x-code-samples` (deprecated), `x-examples`, `x-ignoredHeaderParameters`, `x-nullable`, `x-servers`, `x-traitTag`, `x-additionalPropertiesName`, and `x-explicitMappingOnly` are detected but ignored when extracting custom extensions.

packages/docusaurus-plugin-openapi-docs/README.md

@@ -238,7 +238,7 @@ The plugin extracts a number of vendor extensions from the OpenAPI spec to enric
 | `x-displayName`                            | Overrides tag display names.                                          |
 | `x-enumDescription` / `x-enumDescriptions` | Documents enum values.                                                |
 
-Other ReDoc specific extensions such as `x-circular-ref`, `x-code-samples` (deprecated), `x-examples`, `x-ignoredHeaderParameters`, `x-nullable`, `x-servers`, `x-traitTag`, `x-additionalPropertiesName`, and `x-explicitMappingOnly` are ignored when extracting custom data.
+Circular references flagged with `x-circular-ref` or detected automatically are serialized as `circular(<title>)`. Other ReDoc specific extensions such as `x-code-samples` (deprecated), `x-examples`, `x-ignoredHeaderParameters`, `x-nullable`, `x-servers`, `x-traitTag`, `x-additionalPropertiesName`, and `x-explicitMappingOnly` are ignored when extracting custom data.
 
 ## CLI Usage