Fix typos / spelling in comments

Signed-off-by: Mike Ralphson <mike@abacus.co.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/tree-diff.c b/tree-diff.c
index b05d0f4..edd8394 100644
--- a/tree-diff.c
+++ b/tree-diff.c
@@ -374,7 +374,7 @@
 	}
 
 	/*
-	 * Then, discard all the non-relevane file pairs...
+	 * Then, discard all the non-relevant file pairs...
 	 */
 	for (i = 0; i < q->nr; i++) {
 		struct diff_filepair *p = q->queue[i];