chore(readme): stronger, clearer on node/npm versions

README.md

@@ -15,10 +15,14 @@ Please keep that in mind before posting issues and PRs.
 
 Node.js and npm are essential to Angular 2 development. 
     
-* We certify specific version — node `v5.x.x` and npm `3.x.x` — for this QuickStart. 
-Both older and newer versions produce errors.
+<a href="https://docs.npmjs.com/getting-started/installing-node" target="_blank" title="Installing Node.js and updating npm">
+Get it now</a> if it's not already installed on your machine.
  
-* We recommend [nvm](https://github.com/creationix/nvm) for managing multiple versions of node and npm.
+**Verify that you are running node `v5.x.x` and npm `3.x.x`**
+by running `node -v` and `npm -v` in a terminal/console window.
+Older and newer versions produce errors.
+
+We recommend [nvm](https://github.com/creationix/nvm) for managing multiple versions of node and npm.
 
 ## Create a new project based on the QuickStart