Npm install documentation missing actual installation instruction commands

[bandrei]

Problem:

1. Missing instructions on how to get an actual version of NPM working on the landing page
2. Multiple levels of indirection when trying to set-up NPM is a rather bad pattern.

Proposal

Update the landing page with the instructions from the github repo on how to get NVM install and how to get NPM installed after that so they are on the same page.

Similarly, update the NodeInstaller instructions to be on the same page.