simplify the "no changes added to commit" message

Suggesting the use of [-a|-i|-o] with git-commit is unnecessarily
complex and confusing.  In this context -o is totally useless and -i
requires extra arguments which are not mentioned.  The only sensible
hint (besides reading the man page but let's not go there) is
"commit -a".
Signed-off-by: NNicolas Pitre <nico@cam.org>
Signed-off-by: NJunio C Hamano <junkio@cox.net>

wt-status.c

@@ -335,7 +335,7 @@ void wt_status_print(struct wt_status *s)
 		if (s->amend)
 			printf("# No changes\n");
 		else if (s->workdir_dirty)
-			printf("no changes added to commit (use \"git add\" and/or \"git commit [-a|-i|-o]\")\n");
+			printf("no changes added to commit (use \"git add\" and/or \"git commit -a\")\n");
 		else if (s->workdir_untracked)
 			printf("nothing added to commit but untracked files present (use \"git add\" to track)\n");
 		else if (s->is_initial)