add example for compact inventory

inventories/staging/group_vars/all.yml

@@ -0,0 +1,11 @@
+---
+# to use short names in your inventory file
+# uncomment the following lines.
+# then you can use the hostname as the inventory name
+# and do not need to specify the fqdn.
+
+# host_domain: company.example.com
+# ansible_host: "{{inventory_hostname}}.{{host_domain}}"
+
+# ansible_user: ansible
+# ansible_connection: ssh