Add modification warning to templated files
diff --git a/gRPC-ProtoRPC.podspec b/gRPC-ProtoRPC.podspec
index 4f061d3..85947a7 100644
--- a/gRPC-ProtoRPC.podspec
+++ b/gRPC-ProtoRPC.podspec
@@ -1,3 +1,9 @@
+# This file has been automatically generated from a template file.
+# Please make modifications to
+# `templates/gRPC-ProtoRPC.podspec.template` instead. This file can be
+# regenerated from the template by running
+# `tools/buildgen/generate_projects.sh`.
+
# Copyright 2015, Google Inc.
# All rights reserved.
#