edited README for linux install based on fresh try

[DavidGriswoldTeacher]

What

I edited the part of the Readme that is for installing on Linux to hopefully help others not get caught by some of the issues I had doing this install, hopefully saving some time and googling!

I also added a note in the Windows section that working under a virtual machine is a possibility (that's what I'm trying!)

[stale[bot]]

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