improvement - Bring code-example as readable HTML (#2195)

* Bring code-example as readable HTML

In all other documentation -> column documents there is the source code clearly written, so I missed it in the nested documentation and brought it in. Please verify and thanks for merge 👍

* Added Output of nested_example itself

👍 👍 👍  jgthms for your fast comment! No I can go to bed and sleep well :o) 🌜

docs/documentation/columns/nesting.html

@@ -39,6 +39,7 @@ breadcrumb:
   </p>
 </div>
 
+{% capture columns_nested_example %}
 <div class="columns">
   <div class="column">
     <p class="bd-notification is-info">First column</p>
@@ -66,9 +67,16 @@ breadcrumb:
     </div>
   </div>
 </div>
+{% endcapture %}
+
+{{ columns_nested_example }}
 
 <div class="content">
   <p>
     Multiline columns will also have a <strong>gap</strong> between each <strong>line</strong>.
   </p>
 </div>
+
+<div class="highlight-full">
+  {% highlight html %}{{ columns_nested_example }}{% endhighlight %}
+</div>