docs: expand workspace explanation

[richsoni]

This doc is great! There were a few other places I needed to go to / a couple things that did not read well. Just offering some suggestions to expand this section out

[DanBuild]

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Built with commit 4563ba84140205bed88d76fbaaf4095dfc3ada45

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[Haroenv]

These changes look good, thanks! I'll just ask @arcanis to review this, since he's the most knowledgeable about it 😄

[arcanis]

I'm not sure I want to explain it works via symlinks, since it's not the case starting from PnP 🤔