Add a brand/logo usage page

[danielcompton]

There seems to be a slow but steady flow of people trying to use the Clojure logo in ways that aren't allowed by Rich (unintentionally). It could be good to have a page under Community which talks about the allowed usage of the Clojure logo and the word Clojure as well.

[puredanger]

We've talked about this in the past. Python has some good pages on this.

https://www.python.org/community/logos/
https://www.python.org/psf/trademarks/

The last word on this will need to come from Rich though.

[puredanger]

moving this to backlog for now pending feedback from Rich