docs(links): update deprecated links

update deprecated links
references to the API specs and testing URL brings a not found page

documentation/docs/specs/backend-specs/introduction.md

@@ -5,8 +5,8 @@ sidebar_position: 1
 # Introduction
 
 
-All backend implementations need to adhere to our [API spec](https://github.com/gothinkster/realworld/tree/master/api).
+All backend implementations need to adhere to our [API spec](https://github.com/gothinkster/realworld/tree/main/api).
 
 For your convenience, we have a [Postman collection](https://github.com/gothinkster/realworld/blob/main/api/Conduit.postman_collection.json) that you can use to test your API endpoints as you build your app.
 
-Our [starter kit](https://github.com/gothinkster/realworld-starter-kit) includes [references to the API specs & testing](https://github.com/gothinkster/realworld-starter-kit/blob/master/BACKEND_INSTRUCTIONS.md) required for creating a new backend.
+Check out our [starter kit](https://github.com/gothinkster/realworld-starter-kit) to create a new implementation, please read [references to the API specs & testing](https://gothinkster.github.io/realworld/docs/specs/backend-specs/introduction) required for creating a new backend.