worktree: include repair cmd in usage

The worktree repair command was not added to the usage menu for the
worktree command. This commit adds the usage of 'worktree repair'
according to the existing docs.

Signed-off-by: Des Preston <despreston@gmail.com>
Acked-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/worktree.c

@@ -22,6 +22,7 @@ static const char * const worktree_usage[] = {
 	N_("git worktree move <worktree> <new-path>"),
 	N_("git worktree prune [<options>]"),
 	N_("git worktree remove [<options>] <worktree>"),
+	N_("git worktree repair [<path>...]"),
 	N_("git worktree unlock <path>"),
 	NULL
 };