Update Getting-Started or all three flavors of RAVE

[joewheaton]

Update: https://github.com/Riverscapes/RaveAddIn/blob/master/docs/getting-started.md for showing new users how to use RAVE
This is likely to be where most people get sent when they are provided a link to a Riverscape Project and are not RAVE users already.

This is now ready to populated here:
http://rave.riverscapes.xyz/Software_Help/arcrave_help.html#getting-started
http://rave.riverscapes.xyz/Software_Help/qrave_help.html#getting-started
http://rave.riverscapes.xyz/Software_Help/webrave_help.html#getting-started