Update Docs Documentation on PendingReboot Migration

[PlagueHO]

The following pages on docs.microsoft.com will need to be updated once the PendingReboot migration is complete:
https://github.com/MicrosoftDocs/PowerShell-Docs/blob/staging/dsc/managing-nodes/metaConfig.md
https://github.com/MicrosoftDocs/PowerShell-Docs/blob/staging/dsc/managing-nodes/metaConfig4.md

Will need to get @mgreenegit to update this document on Azure Guest Configuration:
https://docs.microsoft.com/en-us/rest/api/guestconfiguration/guestconfigurationassignments/get