Provide WSL guidance on download page

Moving a convo out of #7650.

@ljharb (in PR Review):

it'd be nice to have a "WSL" option somehow prominent, so that windows users who have WSL can choose nvm, devbox, etc, but atm this seems good

@MattIPv4 (in Issue Comment):

We should move this discussion to an issue, but yeh, either we should update "Linux" to be "Linux (+ WSL)" or add a dedicated "WSL" option in the dropdown. Or, we could display a banner whenever Windows is selected noting that if the user is using WSL, they should refer to the Linux options.

@avivkeller (in Issue Comment):

It's in the name, Windows Subsystem for Linux. IMHO users should be expected to know that if they WSL, they can refer to the Linux instructions

@MattIPv4 (in Issue Comment):

The whole point of this page is to not make assumptions, this page is for beginners that're new to Node.js (and often development generally). They may have heard that WSL is the thing to use for Windows dev, and not know anything beyond that.

@ljharb (in Issue Comment):

Yes, but windows users who are not using or aware of WSL won't know that WSL even exists as an option in the first place such that they could use the things listed under Linux.

Not sure quite what the perfect solution is, but we should have a way to educate Windows users about WSL -- both that it is an option to them alongside conventional Windows development using Powershell, and also that if they do want to use WSL they should follow the Linux install options that we provide.

Start at the download page and review how the Windows and Linux options are presented. Decide how to explain WSL as an option for Windows users and direct those users to the Linux installation guidance; done means the page clearly covers both points without assuming prior WSL knowledge.