Adding a helpful warning message on top of the Makefile and BUILD file.
diff --git a/Makefile b/Makefile
index 8994a78..675f9c1 100644
--- a/Makefile
+++ b/Makefile
@@ -1,5 +1,7 @@
 # GRPC global makefile
 # This currently builds C and C++ code.
+# This file has been automatically generated from a template file.
+# Please look at the templates directory instead.
 
 # Copyright 2015, Google Inc.
 # All rights reserved.