test/[n-r]*.go: add documentation
The rename ones needed redoing.

R=golang-dev, bradfitz, rsc
CC=golang-dev
https://golang.org/cl/5698054
diff --git a/test/reorder2.go b/test/reorder2.go
index 22fefde..d91f1d8 100644
--- a/test/reorder2.go
+++ b/test/reorder2.go
@@ -4,7 +4,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// derived from fixedbugs/bug294.go
+// Test reorderings; derived from fixedbugs/bug294.go.
 
 package main