Fix typo in remote set-head usage
Fix typo in remote set-head usage

parenthesis are not matching in `builtin_remote_sethead_usage`
as a square bracket is closing something never opened.

Signed-off-by: Antoine Pelisse <463d741a21dd6629d7267146d1fda38324b2e9c2@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