This expands gitweb/README to talk some more about GITWEB_CONFIG, moves
feature-specific documentation in gitweb.cgi to the inside of the %features
array, and adds some short description of all the features.
Signed-off-by: NPetr Baudis <pasky@suse.cz>
Signed-off-by: NJunio C Hamano <junkio@cox.net>