Documentation/git-ls-remote.txt: Add -h and -t.

-h and -t are aliases for --heads and --tags to git-ls-remote.
Signed-off-by: NNikolai Weibull <nikolai@bitwi.se>
Signed-off-by: NJunio C Hamano <junkio@cox.net>

Documentation/git-ls-remote.txt

@@ -17,7 +17,7 @@ Displays the references other repository has.
 
 OPTIONS
 -------
---heads --tags::
+-h|--heads, -t|--tags::
 	Limit to only refs/heads and refs/tags, respectively.
 	These options are _not_ mutually exclusive; when given
 	both, references stored in refs/heads and refs/tags are