update wording around extensions

Author: devalog

fern/products/api-def/pages/overrides.mdx

@@ -3,13 +3,15 @@ title: Overrides
 description: Customize your API definition using a separate overrides file.
 ---
 
-Use an overrides file to customize your API definition without modifying the original spec. This is useful when:
+Use an overrides file to customize your OpenAPI, AsyncAPI, OpenRPC, or gRPC definition without modifying the original spec. This is useful when:
 
 * Your API specification is auto-generated from server code
 * You need different configurations for SDKs versus documentation
 
+Overrides are available for OpenAPI, AsyncAPI, OpenRPC, and gRPC specifications. They are not needed for [Fern Definition](/api-definitions/ferndef/overview) since you can directly edit those files.
+
 <Note>
-While you can also embed [Fern extensions](https://buildwithfern.com/learn/api-definitions/openapi/extensions/overview) directly in your API specification, using overrides files is the recommended approach as it keeps your original spec clean and separates concerns.
+While you can also embed [Fern extensions](/api-definitions/overview/overrides#definition-specific-extensions) directly in your API specification, using overrides files is the recommended approach as it keeps your original spec clean and separates concerns.
 </Note>
 
 ## Implement overrides
@@ -32,6 +34,9 @@ fern/
 
 </Step>
 <Step title="Customize your spec with Fern extensions">
+
+For OpenAPI, AsyncAPI, and OpenRPC, and gRPC, you can use [Fern's extensions](/api-definitions/overview/overrides#definition-specific-extensions) to apply customizations. 
+
 ```yml title="overrides.yml" {4-5}
 paths: 
  /users: 
@@ -158,9 +163,9 @@ groups:
         version: 0.8.8
 ```
 
-## Definition-specific customizations
+## Definition-specific extensions
 
-Learn more about the customizations you can make for each definition:
+Learn more about the Fern extensions you can use to customize your definition:
 
 <CardGroup cols={2}>
   <Card title="OpenAPI" href="/api-definitions/openapi/extensions/overview">