Include required RBAC Action(s) for each operation in documentation

[hrboyceiii]

See Azure PowerShell Issue 6843

There are many scenarios where to perform a given operation, there isn't a least-privileged built-in RBAC role that grants the required permissions to perform the operation. Simple examples include restarting a Web App, VM, etc. Other scenarios (which are more complex beyond the rest apis themselves) include granting SQL DB Contributor on a SQL DB doesn't actually allow you to run an ARM deployment as that also requires Microsoft.Resources/deployments/* on the instance's resource group.

Please consider documenting the required RBAC actions per operation so that it is easier to discover and determine when it is appropriate for creating a custom RBAC role.