Add webhooks section to OpenAPI setup (#894)

* add webhooks section

* put version requirements in context

Author: ethanpalm

api-playground/openapi-setup.mdx

@@ -4,7 +4,7 @@ description: "Reference OpenAPI endpoints in your docs pages"
 icon: "file-json"
 ---
 
-OpenAPI is a specification for describing REST APIs. Mintlify supports OpenAPI 3.0+ documents to generate interactive API documentation and keep it up to date.
+OpenAPI is a specification for describing APIs. Mintlify supports OpenAPI 3.0+ documents to generate interactive API documentation and keep it up to date.
 
 ## Add an OpenAPI specification file
 
@@ -186,8 +186,6 @@ version: "version-string" (not required)
 
 <Note>
   The method and path must exactly match the definition in your OpenAPI specification. If the endpoint doesn't exist in the OpenAPI file, the page will be empty.
-
-  For webhooks, use `webhook` (case insensitive) instead of the HTTP method (like `GET` or `POST`) in your reference.
 </Note>
 
 ### Autogenerate `MDX` files
@@ -239,3 +237,29 @@ openapi-schema: "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.
+
+### Define webhooks in your OpenAPI specification
+
+Add a `webhooks` field to your OpenAPI document alongside the `paths` field.
+
+For more information on defining webhooks, see [Webhooks](https://spec.openapis.org/oas/v3.1.0#oasWebhooks) in the OpenAPI documentation.
+
+### Reference webhooks in MDX files
+
+When creating MDX pages for webhooks, use `webhook` instead of HTTP methods like `GET` or `POST`:
+
+```mdx
+---
+title: "Example webhook"
+description: "Triggered when an event occurs"
+openapi: "path/to/openapi-file webhook example-webhook-name"
+---
+```
+
+<Note>
+  The webhook name must exactly match the key defined in your OpenAPI specification's `webhooks` field.
+</Note>