Adding a first (rough) iteration of VSCode setup instructions

This MR adds a first pass of VS Code setup instructions.

The current status of this documentation is that it's more of a "dump" of information rather than a step-by-step guide. Still, I think if anyone has used VSCode before or is interested in learning it using other available tutorials, this information is precious and enough to setup a working environment specific to muon collider software.

There are several things that can and should be done better, but this is a decent start at least. Highest priority would be to have a normal user added to the container, such that we can map to that use the local one and we don't write files as root user when using docker.