Add a section about license information and what data is and is not allowed in OSM

[bgirardot]

Some contributors during a crisis would like to contribute and perhaps do not understand what data we can enter into OSM. It would be good to have a section that talks about this in LearnOSM as we would like LearnOSM to be the "one stop" for learning about putting data into OSM for people looking to learn via a "tutorial" format as opposed to the search around and figure it out wiki format of wiki.osm.org.

[miracle-E]

Is this issue still open?