Tags Followings Endpoint Documentation Needs Updates

[HankG]

• POST endpoint needs to change format so that the tag name isn't on the path but is a parameter {name: value}
• Some of the endpoints will have error responses that have to be flagged that aren't. Will be a 403 error with text of "Failed to process the tag followings request" (as coded right now anyway)

[skyschub]

First point addressed by e601b9d.