1. Dead link to the HA guide. Added a comment regarding
availability and reliability.
2. Hyper-v link re-routed to Azure instead of Hyper-V.
Updated this so it reflects Hyper-V docs.
Suggestion: Might be worth mentioning which Hyper-V servers
ceilometer actually supports.
Change-Id: I4a56ee26ae39ab02bed8bac8d0e364322617622c
backport: stein rocky