Merge pull request #1324 from nicolasnoble/template-warning

Adding a helpful warning message on top of the Makefile and BUILD file.
diff --git a/BUILD b/BUILD
index 8bebe1b..6018c1e 100644
--- a/BUILD
+++ b/BUILD
@@ -1,5 +1,7 @@
 # GRPC Bazel BUILD file.
 # 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.
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.
diff --git a/templates/BUILD.template b/templates/BUILD.template
index fdf87bd..075c399 100644
--- a/templates/BUILD.template
+++ b/templates/BUILD.template
@@ -1,5 +1,7 @@
 # GRPC Bazel BUILD file.
 # 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.
diff --git a/templates/Makefile.template b/templates/Makefile.template
index 73f7945..926c908 100644
--- a/templates/Makefile.template
+++ b/templates/Makefile.template
@@ -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.