builtin/commit.c: fix a typo in the comment

Signed-off-by: Kaartic Sivaraam <kaarticsivaraam91196@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/commit.c

@@ -984,7 +984,7 @@ static int rest_is_empty(struct strbuf *sb, int start)
 	int i, eol;
 	const char *nl;
 
-	/* Check if the rest is just whitespace and Signed-of-by's. */
+	/* Check if the rest is just whitespace and Signed-off-by's. */
 	for (i = start; i < sb->len; i++) {
 		nl = memchr(sb->buf + i, '\n', sb->len - i);
 		if (nl)