remove rkt reference

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Author: hiramf

content/en/docs/tutorials/kubernetes-basics/explore/explore-intro.html

@@ -79,7 +79,7 @@ <h2>Nodes</h2>
                 <p>Every Kubernetes Node runs at least:</p>
                 <ul>
                     <li>Kubelet, a process responsible for communication between the Kubernetes Master and the Node; it manages the Pods and the containers running on a machine.</li>
-                    <li>A container runtime (like Docker, rkt) responsible for pulling the container image from a registry, unpacking the container, and running the application.</li>
+                    <li>A container runtime (like Docker) responsible for pulling the container image from a registry, unpacking the container, and running the application.</li>
                 </ul>
 
             </div>