Specify guidelines on (registered) trademarks (#4278)
Specify guidelines on (registered) trademarks (#4278)

Specify our guidelines on whether or not to include (registered)
trademark symbols in logos as publically discussed.

This also slightly changes the document structure of the Contributing
Guidelines with the goal of making it a little bit easier to find this
new information.
simple-icons/simple-icons,danleech/simple-icons,danleech/simpleicons.org,simple-icons/simple-icons,danleech/simpleicons.org