UAV ROS standards

[knmcguire]

I was notified on some standard messages for UAVS in ROS that somebody wrote a document about:

https://ros.org/reps/rep-0147.html

Might be good to follow some standards for Crazyswarm2 as well? In case we want to externalize some of the messages.

Anyway, I'm just putting it out there for references 🙂