sysadmin/support: Add an howto to connect to the kubernetes running rancher

Related to swh/infra/sysadm-environment#4998 (closed)

docs/sysadm/support-services/rancher/howtos.rst

+.. _rancher_howtos:
+
+.. admonition:: Intended audience
+   :class: important
+
+   sysadm staff members
+
+
+Rancher howtos
+==============
+
+How to connect to the underlying kubernetes
+-------------------------------------------
+
+- Add the following line in your `/etc/hosts`
+
+.. code::
+
+    192.168.200.18 euwest-rancher-3a905e13.1bef1012-0a93-4a25-8419-ac60363bf3d2.privatelink.westeurope.azmk8s.io
+
+
+- Get the cluster credentials
+
+.. code:: bash
+
+    az aks get-credentials --resource-group euwest-rancher --name euwest-rancher  -f rancher-admin.yaml
+
+
+- Test the connectivity
+
+.. code:: bash
+
+    kubectl --kubeconfig rancher-admin.yaml get nodes