best response confirmed by Technodude (Contributor)
Well... I logged a ticket with Microsoft at the same time as posting on here and they've been brilliant and got the issue resolved. So... for anyone reading this...

1) Microsoft are currently working on the documentation and hope to have it live soon.
2) The old CS- cmdlets are all included within the latest 2.5.1 module but... I had to do the following to resolve the issue....

Uninstall-Module MicrosoftTeams (to remove 2.5.1)
Install-Module MicrosoftTeams (without version number) ... this errored and came back telling me I had the MicrosoftTeams module v0.9.6 already installed and to use -force to sideload the 2.5.1 module.
Instead, I was asked to delete the v0.9.6 module from the location specified in the error message
Afterwards, re-ran Install-Module MicrosoftTeams and it installed without error.

Once installed I was able to run the CS- commands without issue. :)