Update message for newer node version

[ghost]

What / Why

This makes the message more clear, since it says you have to use a newer version of node even if the version is too new for npm

It also prevents error messages like this:

npm WARN npm npm does not support Node.js v10.15.2
npm WARN npm You should probably upgrade to a newer version of node as we
npm WARN npm can't make any promises that npm will work with this version.
npm WARN npm Supported releases of Node.js are the latest release of 4, 6, 7, 8, 9.
npm WARN npm You can find the latest version at https://nodejs.org/

[mikemimik]

Hello @raspberrypifan thanks for making a pull-request!

I added the needs discussion label to this issue because I think the team wants to push people towards the latest version, rather than just a newer one. We'll give it a talk over though and definitely get back to you! :D

[darcyclarke]

@raspberrypifan Appreciate the contribution here! That said, I think we're going to leave the current messaging the way it is. We definitely have the "supported versions" logic on our radar to change/improve going forward though (ie. to help address/correct false positives).