[PROPOSAL] Add a section on a formalize error details in HTTP response (following RFC7807)

[dbelyaev]

Problem:

When error happens in API processing developer need to return a code to the user and also some additional information, if possible.

Initially, RFC 7807 has been introduced with the idea to standardize the response for the error reporting from server to client (json and predefined fields, that can be extended).

Before the RFC 7807 started to be wide-spread, Zalando open-sourced their Java library Problem that implemented this standard and supporting classes -- and this was quite popular and adopted quickly.

Nowadays, adoption of the RFC 7807 is a common practice (for example, in Java world: Spring framework implements it via ProblemDetail class which can be used as response on controllers).

Proposal:

Could be a good idea to reference to the RFC 7807 somewhere in the Equinor REST guideline.