Explain 'sudo -E' someplace accessible

Issue triage update by Erik 2021-10-22: this remains relevant.

I suggest a topic guide entry in our documentation about the choices we’ve made to add exempt_group in sudoers to preserve PATH for those users, and how the -E flag is relevant.

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It’s important, but need to figure out where to explain it without complicating things

[kannes]

I would also recommend “-H, --set-home” so that users do not get warnings like

The directory ‘/home/jupyter-adminuser/.cache/pip/http’ or its parent directory is not owned by the current user and the cache has been disabled. Please check the permissions and owner of that directory. If executing pip with sudo, you may want sudo’s -H flag. The directory ‘/home/jupyter-adminuser/.cache/pip’ or its parent directory is not owned by the current user and caching wheels has been disabled. check the permissions and owner of that directory. If executing pip with sudo, you may want sudo’s -H flag.

[fm75]

I have a PR in that adds the -E as part of solving a problem where the installation is behind a proxy.