Better API Docs for Amplify JS V6

**Describe the content issue**:
Amplify document does not contain detailed API reference page for all the methods available in v6 including a list of all Exceptions and Error codes

**URL page where content issue is**:
https://docs.amplify.aws/javascript/build-a-backend/

Our JS API documentation is not clear and hard to navigate. For example we not have list of error codes and exceptions for Authentication.
https://aws-amplify.github.io/amplify-js/api/index.html

Requesting for a JS API reference in amplify docs with v6 content