adding comment to explain json vars

playbooks/roles/edxapp/vars/main.yml

 # variables common to the lms role, automatically loaded
 # when the role is included
 ---
+
+# These vars are for creating the application json config
+# files.  There are two for each service that uses the
+# 'edx-platform' code.  Defining them will create the upstart
+# job and nginx configuration for the corresponding service.
+# It will also enable the corresponding section in the 
+# 'edxapp' upstart job.
+
 lms_auth_config: false
 lms_env_config: false
 lms_preview_auth_config: false