adjust description & give source for nested `.btn-group`s example

components.html

@@ -155,12 +155,11 @@ base_url: "../"
 {% endhighlight %}
 
     <h3 id="btn-groups-nested">Nested button groups</h3>
-    <p>Place buttons groups within button groups when you want dropdown menus mixed with a series of buttons.</p>
+    <p>Place a <code>.btn-group</code> within another <code>.btn-group</code> when you want dropdown menus mixed with a series of buttons.</p>
     <div class="bs-example">
       <div class="btn-group">
         <button type="button" class="btn btn-default">1</button>
         <button type="button" class="btn btn-default">2</button>
-        <button type="button" class="btn btn-default">3</button>
 
         <div class="btn-group">
           <button type="button" class="btn btn-default dropdown-toggle" data-toggle="dropdown">
@@ -170,11 +169,27 @@ base_url: "../"
           <ul class="dropdown-menu">
             <li><a href="#">Dropdown link</a></li>
             <li><a href="#">Dropdown link</a></li>
-            <li><a href="#">Dropdown link</a></li>
-           </ul>
+          </ul>
         </div>
       </div>
     </div>
+{% highlight html %}
+<div class="btn-group">
+  <button type="button" class="btn btn-default">1</button>
+  <button type="button" class="btn btn-default">2</button>
+
+  <div class="btn-group">
+    <button type="button" class="btn btn-default dropdown-toggle" data-toggle="dropdown">
+      Dropdown
+      <span class="caret"></span>
+    </button>
+    <ul class="dropdown-menu">
+      <li><a href="#">Dropdown link</a></li>
+      <li><a href="#">Dropdown link</a></li>
+    </ul>
+  </div>
+</div>
+{% endhighlight %}
 
     <h3 id="btn-groups-vertical">Vertical button groups</h3>
     <p>Make a set of buttons appear vertically stacked rather than horizontally.</p>