Update public_api.md in developer_docs to set UI_ACCESS_TOKEN_ENABLED=true

[SundeepChand]

Nature of issue?

• Existing feature enhancement

Feature enhancement details:

Hello @catarak. While working on #975 it took me a few hours to figure out how to enable access token UI in settings page. I think it would be nice if it is mentioned in the docs to set UI_ACCESS_TOKEN_ENABLED=true in the .env file. I would like to work on this.

[afeefuddin]

Hey @raclim , I want to work on this issue!! Can you assign me this?

[jsndz]

I would also like to work on this issue

[owais0017]

i m new to open source kindly let me work on this

[PiyushThapaa]

i would like to work on this issue please assign it to me