Documentation on Testomatio Tokens

[TetianaKhomenko]

We have tokens but there is no documentation on it.

https://app.testomat.io/account/access_tokens

1. explanation for General Tokens - The General Token provides comprehensive API-driven access to all user projects.
   • how to create, copy and delete General Tokens
2. explanation for Project Tokens - The Project Token makes it possible to gain access only to a specific project for which the token was generated
   • create, copy and delete Project Tokens
   • search by project name

[TetianaKhomenko]

create a page for API Tokens in Advanced section

[liudmylastepanets]

Kindly review my PR #473