Node and npm minimal tested versions added

Summary :
The contrib file is updated with minimal tested version
for node and npm. This is added after facing difficulty
with the quoted commands to update the node/ npm with
errors from fetching the registry.

Solution found at the following URL -
[https://github.com/joyent/node/wiki/Installing-Node.js-via-package-manager#debian-and-ubuntu-based-linux-distributions]

TestPlan :
Local Build by
$ gitbook serve draft_book

Reviewers :
admin

Reported-By :
Swathi V

SignedOff-By :
swatzdev@gmail.com
Merge pull request #1 from SwathiMystery/master

Node and npm minimal tested versions added