[Twig] [twig reference] add examples to function and filters - fix html

Author: Sarah-eit

reference/twig_reference.rst

@@ -551,7 +551,12 @@ FQCN will be shown in a tooltip when a user hovers over the element).
 .. code-block:: twig
 
     {{ 'App\\Entity\\Product'|abbr_class }}
-    {# output: <abbr title="App\Entity\Product">Product</abbr> #}
+
+The above example will be rendered as:
+
+.. code-block:: html
+
+    <abbr title="App\Entity\Product">Product</abbr>
 
 abbr_method
 ~~~~~~~~~~~
@@ -570,7 +575,12 @@ doesn't have a class name, it's shown as a function (``method()``).
 .. code-block:: twig
 
     {{ 'App\\Controller\\ProductController::list'|abbr_method }}
-    {# output: <abbr title="App\Controller\ProductController">ProductController</abbr> #}
+
+The above example will be rendered as:
+
+.. code-block:: html
+
+    <abbr title="App\Controller\ProductController">ProductController</abbr>
 
 format_args
 ~~~~~~~~~~~