Docs for api responses codes

[ResuBaka]

What is the motivation for adding/enhancing this feature?

There should be documentation when to use which API response code. That is going to help people who wants to add new endpoints.

What are the acceptance criteria

• [ ] Have an overview when to use which http status code

Can you complete this feature request by yourself?

• [ ] YES
• [x] NO

Additional information

For the status codes maybe we want to use a library that exports every status code or we could implement it our self? For library's there were:

• http-status-codes