Changing to proto, app, port format

bookstack.subdomain.conf.sample

@@ -1,3 +1,4 @@
+# make sure that your dns has a cname set for bookstack and that your bookstack container is named bookstack
 # Ensure you have the APP_URL Environment Variable set correctly in your Docker Run/Compose or in BookStack Env File (/www/.env)
 # https://github.com/linuxserver/docker-bookstack#docker
 
@@ -22,7 +23,10 @@ server {
 
         include /config/nginx/proxy.conf;
         resolver 127.0.0.11 valid=30s;
-        set $upstream_bookstack bookstack;
-        proxy_pass http://$upstream_bookstack:80;
+        set $upstream_app bookstack;
+        set $upstream_port 80;
+        set $upstream_proto http;
+        proxy_pass $upstream_proto://$upstream_app:$upstream_port;
+
     }   
 }