Hi NZDev,
What we have found is there is not a list of all Dynamics 365 SDK versions.
There is an SDK version for each Major version of D365 (10.0.5, 10.0.6. 10.0.7, etc, etc).
For each of these versions, whenever we ship a quality update for that Major version, an SDK revision update will be in it.
Because the SDK updates are self-contained, we always place it into a new updates folder.
Hopefully this helps.
Todd Berger
Support Escalation Engineer / Microsoft Dynamics 365 Commerce
North America Customer Services and Support