Add warning header to salt-generated files

firewalld/files/direct.xml

 <?xml version="1.0" encoding="utf-8"?>
+<!--
+  This file is managed/generated by salt.
+  Do not edit this file manually, it will be overwritten!
+  Modify the salt pillar for firewalld instead
+-->
 <direct>
   {%- if 'chain' in direct %}
   {%- for k, v in direct.chain.items() %}

firewalld/files/firewalld.conf

 {% set firewalld  = pillar.get('firewalld', {}) -%}
+#
+#  This file is managed/generated by salt.
+#  Do not edit this file manually, it will be overwritten!
+#  Modify the salt pillar for firewalld instead
+#
 # firewalld config file
 
 # default zone

firewalld/files/ipset.xml

 <?xml version="1.0" encoding="utf-8"?>
+<!--
+  This file is managed/generated by salt.
+  Do not edit this file manually, it will be overwritten!
+  Modify the salt pillar for firewalld instead
+-->
 <ipset{%- if 'type' in ipset %} type="{{ ipset.type }}" {%- endif %}>
 {%- if 'short' in ipset %}
   <short>{{ ipset.short }}</short>

firewalld/files/service.xml

 <?xml version="1.0" encoding="utf-8"?>
+<!--
+  This file is managed/generated by salt.
+  Do not edit this file manually, it will be overwritten!
+  Modify the salt pillar for firewalld instead
+-->
 <service version="1">
   {% if 'short' in service %}<short>{{ service.short }}</short>{%- else %}<short>{{ name }}</short>{%- endif %}
   {% if 'description' in service %}<description>{{ service.description }}</description>{%- endif %}

firewalld/files/zone.xml

 <?xml version="1.0" encoding="utf-8"?>
+<!--
+  This file is managed/generated by salt.
+  Do not edit this file manually, it will be overwritten!
+  Modify the salt pillar for firewalld instead
+-->
 <zone{%- if 'target' in zone %} target="{{ zone.target }}"{%- endif %}>
   {% if 'short' in zone %}<short>{{ zone.short }}</short>{% else %}<short>{{ name }}</short>{% endif %}
   {% if 'description' in zone %}<description>{{ zone.description }}</description>{% endif %}