Display "managed by Salt" header in user sudoers files

users/init.sls

       {%- endfor %}
       {%- endif %}
       {%- if 'sudo_rules' in user %}
+        ########################################################################
+        # File managed by Salt (users-formula).
+        # Your changes will be overwritten.
+        ########################################################################
+        #
       {%- for rule in user['sudo_rules'] %}
         {{ name }} {{ rule }}
       {%- endfor %}
     - require:
       - file: users_sudoer-defaults
       - file: users_sudoer-{{ name }}
-  cmd.wait:                                                                           
+  cmd.wait:
     - name: visudo -cf {{ users.sudoers_dir }}/{{ name }} || ( rm -rvf {{ users.sudoers_dir }}/{{ name }}; exit 1 )
-    - watch:                                                                         
-      - file: {{ users.sudoers_dir }}/{{ name }}   
+    - watch:
+      - file: {{ users.sudoers_dir }}/{{ name }}
 {% endif %}
 {% else %}
 users_{{ users.sudoers_dir }}/{{ name }}: