MultiDock 2 USB panel-mount socket adaptor

Adaptor plate to use a generic panel-mount USB socket in a Griffin MultiDock 2 (as a replacement for an original riser card). This was designed as part of the [STFDock project](https://hackaday.io/project/21320-stfdock/), which involved turning a MultiDock 2 into a self-contained (just supply power and plug devices in) OpenSTF device lab.

The panel-mount USB sockets I used required some trimming with a sharp knife in order to account for the raised section which corresponds to the thin edge