Go to servercmdline.txt in /config and scroll down to where it says:
Take off the first two /'s in front of -M.
Now put cUR after -M so it looks like:
Now anybody can upload maps and admins can update and revert maps.
[SELECT ALL] Code:
//-M // sendmap permission string
Now put cUR after -M so it looks like:
[SELECT ALL] Code:
-McUR // sendmap permission string