docs(accordion): remove unnecessary div

- Remove unnecessary div creating a doubled border

Closes #6378

Author: wesleycho

src/accordion/docs/demo.html

@@ -1,18 +1,16 @@
 <div ng-controller="AccordionDemoCtrl">
   <script type="text/ng-template" id="group-template.html">
-    <div class="panel panel-default">
-      <div class="panel-heading">
-        <h4 class="panel-title" style="color:#fa39c3">
-          <a href tabindex="0" class="accordion-toggle" ng-click="toggleOpen()" uib-accordion-transclude="heading">
-            <span uib-accordion-header ng-class="{'text-muted': isDisabled}">
-              {{heading}}
-            </span>
-          </a>
-        </h4>
-      </div>
-      <div class="panel-collapse collapse" uib-collapse="!isOpen">
-        <div class="panel-body" style="text-align: right" ng-transclude></div>
-      </div>
+    <div class="panel-heading">
+      <h4 class="panel-title" style="color:#fa39c3">
+        <a href tabindex="0" class="accordion-toggle" ng-click="toggleOpen()" uib-accordion-transclude="heading">
+          <span uib-accordion-header ng-class="{'text-muted': isDisabled}">
+            {{heading}}
+          </span>
+        </a>
+      </h4>
+    </div>
+    <div class="panel-collapse collapse" uib-collapse="!isOpen">
+      <div class="panel-body" style="text-align: right" ng-transclude></div>
     </div>
   </script>