apply: fix grammar error in comment

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

apply.c

@@ -4055,7 +4055,7 @@ static int preimage_oid_in_gitlink_patch(struct patch *p, struct object_id *oid)
 	return get_oid_hex(p->old_sha1_prefix, oid);
 }
 
-/* Build an index that contains the just the files needed for a 3way merge */
+/* Build an index that contains just the files needed for a 3way merge */
 static int build_fake_ancestor(struct apply_state *state, struct patch *list)
 {
 	struct patch *patch;