Added Rancher <-> Ubuntu k8s integration documentation (#7607)

* fixed the interacting with cluster section for the ubuntu installation

* made changes as per request from zacharysarah

* added rancher stub

* added rancher documentation

* fixed missing capture tag

* added ingress example, fixed languages as per changes in the PR

* fixed page index as per pr

* fixed rancher readme

_data/setup.yml

@@ -94,7 +94,7 @@ toc:
         - docs/getting-started-guides/ubuntu/glossary.md
         - docs/getting-started-guides/ubuntu/local.md
         - docs/getting-started-guides/ubuntu/logging.md
-
+        - docs/getting-started-guides/ubuntu/rancher.md
     - docs/getting-started-guides/windows/index.md
 
   - docs/admin/node-conformance.md