git-stash: Display help message if git-stash is run with wrong sub-commands
git-stash: Display help message if git-stash is run with wrong sub-commands

The current git-stash behaviour is very error prone to typos. For example,
if you typed "git-stash llist", git-stash would think that you wanted to
save to a stash named "llist", but in fact, you meant "git-stash list".

Signed-off-by: Kevin Leung <13d76c4c7838d91316e121dc6c66461ed5b1f4e1@gmail.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