Update protocols-UAV.md

[rickw-ward]

I'm opening this to edit the UAV protocols.

[dlebauer]

I added a stub to describe the datasets. However, I don't think we've uploaded these yet (https://github.com/terraref/computing-pipeline/issues/167 ?). Might be a good time to do this and review / close related issues and incorporate relevant information into the documentation:

• https://github.com/terraref/computing-pipeline/issues/185
• https://github.com/terraref/computing-pipeline/issues/186
• https://github.com/terraref/documentation/issues/96

[dlebauer]

I've merged this draft into the documentation. Still needs work but closing for now