Monitoring extension documentation addition (#2740)
Monitoring extension documentation addition (#2740)

* add acs-engine monitoring extension section for monitoring docs

* add further post deployment experience documentation

* fix monitoring extension doc suggested changes

jackfrancis/acs-engine,rjtsdl/acs-engine,Azure/acs-engine,rjtsdl/acs-engine,jackfrancis/acs-engine,Azure/acs-engine,jackfrancis/acs-engine,jackfrancis/acs-engine,Azure/acs-engine,rjtsdl/acs-engine,rjtsdl/acs-engine,rjtsdl/acs-engine,Azure/acs-engine,jackfrancis/acs-engine,Azure/acs-engine