Update the rstudio-workbench README.md

[jforest]

The current README.md has a section labelled Required Configuration that explains what to do in the event you are NOT having it create homeStorage for you. If you are mounting up a specific PVC, it has a lot of different steps. While working through this, and looking for documentation on the dcf format so I could add a section for config.serverDcf.launcher-mounts I was informed that there is an easier way using new values!

There are a couple of new values that make life easier for mounting up a PVC to workbench and the launcher sessions:

helm/charts/rstudio-workbench/values.yaml

Lines 105 to 108 in c20af53

	# -- The name of the pvc. By default, computes a value from the release name
	name: ""
	# -- Whether the persistentVolumeClaim should be mounted (even if not created)
	mount: false

These should be explained in the Required Configuration section, rather than the longer and more complicated procedure for setting pod mounts and launcher mounts.

[jforest]

side note, I tried unsetting the pod mounts and it didn't work, so maybe those are still needed even if you set homeStorage.name and homeStorage.mount? 🤷