Add README for zabbix.

software/zabbix-agent/README.rst

+============================
+Zabbix Agent Software Release
+=============================
+
+This Software Release allow to deploy a Zabbix Agent instance.
+
+Please see http://www.zabbix.com/ for more informations.
+
+
+Mandatory parameters
+====================
+
+hostname
+--------
+Name of the machine probed by the agent.
+
+server
+------
+list of Zabbix servers to connect to, comma-seperated.
+
+Optional parameters
+===================
+
+custom-user-parameter
+---------------------
+Add custom UserParameter(s) lines to the Zabbix Agent configuration file.
+
+
+Examples of instance parameters XML
+===================================
+
+Deploy a Zabbix Agent instance for machine named "mymachine" connecting to a Zabbix server accessible from 2001:41d0:1:9b1a::1::
+
+  <?xml version="1.0" encoding="utf-8"?>
+  <instance>
+  <parameter id="server">2001:41d0:1:9b1a::1</parameter>
+  <parameter id="hostname">mymachine</parameter>
+  </instance>
+
+Deploy a Zabbix Agent instance for machine named "mymachine" connecting to a Zabbix server accessible from 2001:41d0:1:9b1a::1, with several custom parameters::
+
+  <?xml version="1.0" encoding="utf-8"?>
+  <instance>
+  <parameter id="server">2001:41d0:1:9b1a::1</parameter>
+  <parameter id="hostname">mymachine</parameter>
+  <parameter id="custom-user-parameter">
+  UserParameter=custom_random,echo $RANDOM
+  UserParameter=custom_date,date</parameter>
+  </instance>
+