Use the injected REST API docs instead of redirecting to the playgound app

[MustafaJafar]

Changelog Description

• resolve Use the injected REST API docs instead of redirecting to the playgound app #378
• use /api instead of https://playground.ayon.app/doc/api for REST API Docs link in the rest api doc page and the dev resources drop down menu.
• add another REST API Docs button on the top right (since this is the only api doc that are injected to the dev docs.)

Testing notes:

1. build the docs.

[antirotor]

LGTM