Improve install docs

[cgmonroe]

It is common practice for security minded organization, e.g. US gov, to not allow normal users to do sudo but instead have an admin account you need to su into to run things needed sudo.

Currently, if you try doing su {admin}, then running the standard install. Thing go bad quickly. Especially if you have used the old lando and have Docker linked to your normal account.

The solution for this situation seems to be:

• dl the install script (per advanced install)
• run the 'bash setup-lando.sh --no-setup' command as the admin user that can do sudo.
• run 'lando setup' as the normal user.

This was found after a lot of blood sweat and tears!

Please document this common use case. This might also be applicable to shared dev machines. E.g. admin installs lando base code. Individuals run lando setup as needed.