Simple description. It appears to be mostly internal command, but hey, it
is (it seems) the only undocumented one, so let's fix it up...
Also add a note about it to git-merge documentation.
Signed-off-by: Petr Baudis <pasky@suse.cz>
Signed-off-by: Junio C Hamano <junkio@cox.net>
Petr Baudis