add README.md file
add README.md file

Change-Id: I0acc1c57bb2b3ce1c8580dc79d010e3075d00d8b

sbrimhall/fuel-plugin-external-zabbix,stackforge/fuel-plugin-external-zabbix,stackforge/fuel-plugin-external-zabbix,stackforge/fuel-plugin-external-zabbix,sbrimhall/fuel-plugin-external-zabbix,sbrimhall/fuel-plugin-external-zabbix,sbrimhall/fuel-plugin-external-zabbix,stackforge/fuel-plugin-external-zabbix