Added distro check

Abort processing if target does not seem to be a Proxmox box

roles/pve-subscribe/tasks/main.yml

@@ -1,5 +1,9 @@
 ---
 
+- name: Assert incompatible target
+  fail: msg="Target doesn't look like a Proxmox instance. Proceeding would cause damage to the target."
+  when: ansible_facts.cmdline.BOOT_IMAGE.find('-pve') == -1
+
 - name: Configuring pve for unsubscribed operation
   import_tasks: no-subscription.yml
   when: pve_enterprise | default(False) != True