git-completion: Add git help completion for aliases
git-completion: Add git help completion for aliases

Enable bash completion for "git help <alias>", analogous to "git
<alias>", which was already implemented.

Signed-off-by: Jakob Pfender <633dd20bc98244b59cb09ea6c3e83a1f2f34c3e9@elegosoft.com>
Signed-off-by: Junio C Hamano <a6723cc3f76163bf7adb636a73ac3b0ceb3e6b9b@pobox.com>

destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git