Update overrides.mdx

Add a link to Fern extensions in the overides page

Author: mattblank11

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

@@ -9,7 +9,7 @@ Use an overrides file to customize your API definition without modifying the ori
 * You need different configurations for SDKs versus documentation
 
 <Note>
-While you can also embed Fern extensions 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](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.
 </Note>
 
 ## Implement overrides
@@ -31,8 +31,7 @@ fern/
 <Note> The format of the overrides file is independent from the spec. For example, even if your OpenAPI spec is in JSON format, you can write the overrides in yaml. </Note>
 
 </Step>
-<Step title="Add customizations">
-
+<Step title="Customize your spec with Fern extensions">
 ```yml title="overrides.yml" {4-5}
 paths: 
  /users: 
@@ -172,4 +171,4 @@ Learn more about the customizations you can make for each definition:
   </Card>
   <Card title="gRPC" href="/api-definitions/grpc/extensions/overview">
   </Card>
-</CardGroup>
+</CardGroup>