Added pre_task to verify minimum Ansible version (#454)

site.yml

@@ -1,4 +1,13 @@
 ---
+- name: Pre tasks
+  hosts: all
+  pre_tasks:
+    - name: Verify Ansible is version 2.11 or above. (If this fails you may need to update Ansible)
+      assert:
+        that: "ansible_version.full is version_compare('2.11', '>=')"
+        msg: >
+          "Ansible is out of date. See here for more info: https://docs.technotim.live/posts/ansible-automation/"
+
 - name: Prepare Proxmox cluster
   hosts: proxmox
   gather_facts: true