* Change generated documentation to indicate what image selection
options are required, and when.
* Refactor the structure of the documentation to highlight required
options for different types of builds
Updates azure builder to support setting end-of-life-date for
image versions in shared image gallery. In addition, this change adds
the ability to set the global replica count for the image version
and allows the vms deployed from the latest version of the Image
Definition to exclude this Image Version.