Documentation: change "gitlink" typo in git-push

The git-push manual page used "gitlink" in one place instead of
"linkgit".  Fix this so the link renders correctly.

Noticed-by: Dan Allen <dan.j.allen@gmail.com>
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git-push.txt

@@ -33,7 +33,7 @@ When the command line does not specify what to push with `<refspec>...`
 arguments or `--all`, `--mirror`, `--tags` options, the command finds
 the default `<refspec>` by consulting `remote.*.push` configuration,
 and if it is not found, honors `push.default` configuration to decide
-what to push (See gitlink:git-config[1] for the meaning of `push.default`).
+what to push (See linkgit:git-config[1] for the meaning of `push.default`).
 
 
 OPTIONS[[OPTIONS]]