add filename in openapi-schema frontmatter docs

Author: lawreka

api-playground/openapi-setup.mdx

@@ -508,6 +508,24 @@ openapi-schema: "schema-key"
 
 </CodeGroup>
 
+If you have the schemas with the same name in multiple files, you can also specify the OpenAPI file:
+
+<CodeGroup>
+
+```mdx Example
+---
+openapi-schema: en-schema.json OrderItem
+---
+```
+
+```mdx Format
+---
+openapi-schema: "path-to-schema-file schema-key"
+---
+```
+
+</CodeGroup>
+
 ## Webhooks
 
 Webhooks are HTTP callbacks that your API sends to notify external systems when events occur. Webhooks are supported in OpenAPI 3.1+ documents.