Update the documentation of the file local_vars.py

Refs: 72521

deploy/local_vars.py

@@ -2,10 +2,10 @@
 # WARNING WARNING WARNING
 #********************************
 
-# YOU MUST NOT MODIFY THIS FILE!
+# YOU MUST COPY THIS FILE IN THE SUBMODULE DIRECTORY FOLDER
 
-# If you need to override the values of the variables defined in this file you should
-# Copy and paste this file with the name local_vars.py and set your values there.
+# If you want to override the variable definitions of the submodule drupy, you must
+# copy and paste this file in the directory of the submodule so it can be imported.
 
 # When you create a file local_vars.py and define the values there, the fabfile.py file will use
 # your values and not the values defined in this file.