Document proposed token gate feature

[0xean]

Background

We have been kicking around this idea of a token gate that would check a balance of a caller prior to a data provider serving the request. There are several differing ideas of what this feature actually looks like and before we move forward we should have some concise documentation so everyone agrees on what we are building before we begin implementation

AC

1. Document the token gate feature
2. present to stakeholders at Tuesday meeting or similar
3. gather feedback and revise doc
4. Create follow up ticket for implementation

[0xean]

Not required for initial launch