docs: update node and npm version recommendations

closes #1821

Author: Foxandxss

public/docs/ts/latest/cli-quickstart.jade

@@ -33,7 +33,7 @@ h2#devenv Step 1. Set up the Development Environment
   if they are not already on your machine.
 .l-sub-section
   :marked
-    **Verify that you are running node `v5.x.x` and npm `3.x.x`**
+    **Verify that you are running node `v4.x.x` and npm `3.x.x`**
     by running `node -v` and `npm -v` in a terminal/console window.
     Older versions produce errors.
 :marked

public/docs/ts/latest/guide/npm-packages.jade

@@ -10,7 +10,7 @@ include ../_util-fns
     <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
 
-    **Verify that you are running at least node `v5.x.x` and npm `3.x.x`**
+    **Verify that you are running at least node `v4.x.x` and npm `3.x.x`**
     by running `node -v` and `npm -v` in a terminal/console window.
     Older versions produce errors.
 

public/docs/ts/latest/quickstart.jade

@@ -52,7 +52,7 @@ block setup-tooling
     if they are not already on your machine.
   .l-sub-section
     :marked
-      **Verify that you are running at least node `v5.x.x` and npm `3.x.x`**
+      **Verify that you are running at least node `v4.x.x` and npm `3.x.x`**
       by running `node -v` and `npm -v` in a terminal/console window.
       Older versions produce errors.