Improve documentation for restricted enterprise install

I work at a corp that does not allow local admin access for the main user id (which uses a domain logon). Corp also blocks windows store.

The only admin access allowed is to a secondary, local user id.

The solution I did, adapting from [this page ](https://www.omgubuntu.co.uk/how-to-install-wsl2-on-windows-10) was this:

1) Log in as secondary user (administrator), and run elevated command prompt "as administrator". Run these commands in it:

dism.exe /online /enable-feature /featurename:Microsoft-Windows-Subsystem-Linux /all /norestart

dism.exe /online /enable-feature /featurename:VirtualMachinePlatform /all /norestart

wsl --set-default-version 2

2) Log back in as main user (not administrator) and run these commands:

wsl --update # Note: unsure if this should/could be run as admin instead

wsl --install --download Ubuntu

Note that you get "Catastrophic error" if you run the simple `wsl --install` as the wrong user id, even though it's an administrator. That's what I tried first, and [saw this ticket](https://github.com/microsoft/WSL/issues/9420) where someone had the same problem. Thus, the need for splitting up the admin vs non-admin steps.