Update links in home, header, footer, whatisk8s (#3833)

* home page, header, footer

* docs/whatisk8s

* /docs/user-guide/compute-resources/

* /docs/concepts/overview/what-is-kubernetes.md

_includes/header.html

@@ -5,7 +5,7 @@
 
     <div class="nav-buttons" data-auto-burger="primary">
         <ul class="global-nav">
-            <li><a href="/docs/home">Documentation</a></li>
+            <li><a href="/docs/home/">Documentation</a></li>
             <li><a href="http://blog.kubernetes.io/">Blog</a></li>
             <li><a href="/partners/">Partners</a></li>
             <li><a href="/community/">Community</a></li>
@@ -19,11 +19,11 @@
     <nav id="mainNav">
         <main data-auto-burger="primary">
         <div class="nav-box">
-            <h3><a href="/docs/hellonode/">Get Started</a></h3>
+            <h3><a href="/docs/tutorials/stateless-application/hello-minikube/">Get Started</a></h3>
             <p>Ready to get your hands dirty? Build a simple Kubernetes cluster that runs "Hello World" for Node.js.</p>
         </div>
         <div class="nav-box">
-            <h3><a href="/docs/home">Documentation</a></h3>
+            <h3><a href="/docs/home/">Documentation</a></h3>
             <p>Learn how to use Kubernetes with the use of walkthroughs, samples, and reference documentation. You can even <a href="/editdocs/" data-auto-burger-exclude>help contribute to the docs</a>!</p>
         </div>
         <div class="nav-box">