mode instruction to view demo pages (symfony 3+)

README.md

@@ -100,7 +100,9 @@ Or you can use the following method:
           }
 ```
 
-Optional: If you want to see the demo page, add the following to your routing.yml (requires Twig):
+# Demo pages
+
+This is optional: If you want to see the demo page, add the following to your routing.yml:
 
 ``` yaml
     _demo:
@@ -109,6 +111,14 @@ Optional: If you want to see the demo page, add the following to your routing.ym
         prefix:   /gchart
 ```
 
+You should have `templating` installed (`php ../composer.phar require templating`) and should have activated it in `config/packages/framework.yml: 
+
+```
+framework:
+    templating:
+        engines: ['twig']
+```
+
 Then you should be able to go to http://your.site.com/gchart/demo
 
 Don't forget to include the required javascript in your layout, for example: