Document OS version support

[TheJaredWilcurt]

I'd like to replace the following in my repos:

1. Install a node version manager:
   * Linux/OSX - https://github.com/nvm-sh/nvm
   * Window 7 - https://github.com/nullivex/nodist
   * Windows 8+ - https://github.com/coreybutler/nvm-windows

with

1. Install a node version manager:
   * https://volta.sh

But there is no documentation for what specific OS's you do and don't support. Which makes me very leary to even try Volta. All I can find is "we support everything!" which... of course you don't, you don't work on Windows 95, and that's fine. I just wanna know what you do and don't support, bonus if you say how long you'll continue supporting an OS version.

This should be in the documentation on the website in the sidebar as "OS Support" with a detailed list of all the OS's. Or at the very least in the README.md.

Example:

• https://github.com/nwutils/create-desktop-shortcuts#os-support

[TheJaredWilcurt]

Follow up, I'm on a Windows 7 laptop at the moment. It apparently has nodist and nvm-windows on it already. Added Volta without even removing the others and it works great! Didn't have to do anything special, just downloaded the installer, ran it, opened cmd and installed Node and npm. Honestly the easiest experience on Win 7 of the 3. Would still like to see an official list of supported OS's on the site though.

Tested good:

• Windows 7 64-bit
• Ubuntu 18.0.4.3 64-bit

Tested bad:

• OSX 10.11 - I have this as a VM, but pretty sure the certs on it expired preventing Volta from installing

[chriskrycho]

Thanks for calling this out! I think we could pretty easily say what we have official builds for, at a minimum, and then clarify that lots of things we don't have official builds for will also work, but aren't tested or officially supported.