Document how to use this with RStudio

[yuvipanda]

When used inside containers, RStudio doesn't actually inherit from the environment variables that JupyterHub sets. I think it needs to be in Renviron.

Let's just document how to do this.

[cboettig]

related: (edited): https://github.com/berkeley-dsep-infra/datahub/issues/5551

[yuvipanda]

Hmm, am not sure how that is related @cboettig! It is so funny that I now have no memory of ever participating in that thread haha :)

[cboettig]

whoops I meant this one: https://github.com/berkeley-dsep-infra/datahub/issues/5551

[yuvipanda]

Ah, that sounds great! I like the extraFiles approach there.