Fix erroneous error message saying "git sync"

It's `git codereview sync`.

Change-Id: Ia55db061d0cf35cb56c6faba7bb1569e621f9b57
GitHub-Last-Rev: 539f4d0750845686c1b0d3720f598f489dc3530f
GitHub-Pull-Request: golang/review#11
Reviewed-on: https://go-review.googlesource.com/128075
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
diff --git a/git-codereview/change.go b/git-codereview/change.go
index 782b2d7..7507973 100644
--- a/git-codereview/change.go
+++ b/git-codereview/change.go
@@ -62,7 +62,7 @@
 		// TODO(rsc): Test.
 		b.loadPending()
 		if n := b.CommitsBehind(); n > 0 {
-			printf("warning: %d commit%s behind %s; run 'git sync' to update.", n, suffix(n, "s"), b.OriginBranch())
+			printf("warning: %d commit%s behind %s; run 'git codereview sync' to update.", n, suffix(n, "s"), b.OriginBranch())
 		}
 	}