Remove custom example plugin. (#25784)

docs/4.0/components/button-group.md

@@ -10,13 +10,14 @@ toc: true
 
 Wrap a series of buttons with `.btn` in `.btn-group`. Add on optional JavaScript radio and checkbox style behavior with [our buttons plugin]({{ site.baseurl }}/docs/{{ site.docs_version }}/components/buttons/#button-plugin).
 
-{% example html %}
+{% capture example %}
 <div class="btn-group" role="group" aria-label="Basic example">
   <button type="button" class="btn btn-secondary">Left</button>
   <button type="button" class="btn btn-secondary">Middle</button>
   <button type="button" class="btn btn-secondary">Right</button>
 </div>
-{% endexample %}
+{% endcapture %}
+{% include example.html content=example %}
 
 {% capture callout %}
 ##### Ensure correct `role` and provide a label
@@ -31,7 +32,7 @@ In addition, groups and toolbars should be given an explicit label, as most assi
 
 Combine sets of button groups into button toolbars for more complex components. Use utility classes as needed to space out groups, buttons, and more.
 
-{% example html %}
+{% capture example %}
 <div class="btn-toolbar" role="toolbar" aria-label="Toolbar with button groups">
   <div class="btn-group mr-2" role="group" aria-label="First group">
     <button type="button" class="btn btn-secondary">1</button>
@@ -48,11 +49,12 @@ Combine sets of button groups into button toolbars for more complex components.
     <button type="button" class="btn btn-secondary">8</button>
   </div>
 </div>
-{% endexample %}
+{% endcapture %}
+{% include example.html content=example %}
 
 Feel free to mix input groups with button groups in your toolbars. Similar to the example above, you'll likely need some utilities though to space things properly.
 
-{% example html %}
+{% capture example %}
 <div class="btn-toolbar mb-3" role="toolbar" aria-label="Toolbar with button groups">
   <div class="btn-group mr-2" role="group" aria-label="First group">
     <button type="button" class="btn btn-secondary">1</button>
@@ -82,7 +84,8 @@ Feel free to mix input groups with button groups in your toolbars. Similar to th
     <input type="text" class="form-control" placeholder="Input group example" aria-label="Input group example" aria-describedby="btnGroupAddon2">
   </div>
 </div>
-{% endexample %}
+{% endcapture %}
+{% include example.html content=example %}
 
 ## Sizing
 
@@ -118,7 +121,7 @@ Instead of applying button sizing classes to every button in a group, just add `
 
 Place a `.btn-group` within another `.btn-group` when you want dropdown menus mixed with a series of buttons.
 
-{% example html %}
+{% capture example %}
 <div class="btn-group" role="group" aria-label="Button group with nested dropdown">
   <button type="button" class="btn btn-secondary">1</button>
   <button type="button" class="btn btn-secondary">2</button>
@@ -133,7 +136,8 @@ Place a `.btn-group` within another `.btn-group` when you want dropdown menus mi
     </div>
   </div>
 </div>
-{% endexample %}
+{% endcapture %}
+{% include example.html content=example %}
 
 ## Vertical variation