docs: #824: Python version upgrade steps broken

[bigpick]

• Add / update documentation

Information

See #824; steps in documentation to upgrade python version don't seem to properly install required packages, and by default stuff them all into the current user's ~/.local/bin if run from a terminal on the box hosting the hub.

This also fixes an issue with the sudo commands still not being able to see conda even though the PATH was passed, since the env was missing.

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