Move webapp_hosts variable into host_vars/

frontend.yml

@@ -3,9 +3,6 @@
   hosts: [frontend]
   roles:
     - role: frontend
-  vars:
-    webapp_hosts:
-      - tusky.masto.yttrx.com
 
   handlers:
   - name: Re-up docker containers

roles/frontend/vars/main.yml

@@ -1 +1,3 @@
 ---
+# The hosts where nginx proxies ports 3000 and 4000 to
+#webapp_hosts: []