Update k8s/tutorials-index.md to add a period (#865)

pages/k8s/tutorials-index.md

@@ -13,7 +13,7 @@ layout: [base, ubuntu-com]
 toc: False
 ---
 
-This section of our documentation contains step-by-step tutorials to guide you through installing and using **Charmed Kubernetes**
+This section of our documentation contains step-by-step tutorials to guide you through installing and using **Charmed Kubernetes**.
 Our tutorials have been written to make as few assumptions as possible, and to be accessible to everyone. They're an ideal place to start learning.
 
 | Tutorial |  |
@@ -35,4 +35,4 @@ Take a look at our _Reference section_ when  you need to know more about version
     <a href="https://github.com/charmed-kubernetes/kubernetes-docs/issues/new">file a bug here</a>.</p>
     <p>See the guide to <a href="/kubernetes/docs/how-to-contribute"> contributing </a> or discuss these docs in our <a href="https://chat.charmhub.io/charmhub/channels/kubernetes"> public Mattermost channel</a>.</p>
   </div>
-</div>
+</div>