Complete Admiral section in vic-product SUPPORT.md

[andrewtchin]

This guide is targeted to GSS and VIC product developers who may handle escalations related to Admiral in the VIC appliance
https://github.com/vmware/vic-product/blob/master/installer/docs/SUPPORT.md

Please fill out this section https://github.com/vmware/vic-product/blob/master/installer/docs/SUPPORT.md#admiral

[andrewtchin]

This should include documentation of common errors and example error logs that would appear when they occur. It is currently very difficult to determine the root cause based on error logs, so improvements in providing clear error messages instead of a stacktrace would be welcome and improve serviceability.