Documentation: Add gitweb config variables to git-config(1)

Add a list of gitweb config variables to git-config(1) manpage, just
linking to gitweb(1) or gitweb.conf(5).

Signed-off-by: Jakub Narebski <jnareb@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/config.txt

@@ -1064,6 +1064,23 @@ All gitcvs variables except for 'gitcvs.usecrlfattr' and
 is one of "ext" and "pserver") to make them apply only for the given
 access method.
 
+gitweb.category::
+gitweb.description::
+gitweb.owner::
+gitweb.url::
+	See linkgit:gitweb[1] for description.
+
+gitweb.avatar::
+gitweb.blame::
+gitweb.grep::
+gitweb.highlight::
+gitweb.patches::
+gitweb.pickaxe::
+gitweb.remote_heads::
+gitweb.showsizes::
+gitweb.snapshot::
+	See linkgit:gitweb.conf[5] for description.
+
 grep.lineNumber::
 	If set to true, enable '-n' option by default.