corrected aria-hidde_ to aria-hidden

I notice the aria-hidden value was incomplete.  

cheers

src/_includes/examples/fixed-width.html

@@ -9,10 +9,10 @@
   <div class="row">
     <div class="col-md-3 col-sm-4">
       <div class="list-group">
-        <a class="list-group-item" href="#"><i class="fa fa-home fa-fw" aria-hidde="true"></i>&nbsp; Home</a>
-        <a class="list-group-item" href="#"><i class="fa fa-book fa-fw" aria-hidde="true"></i>&nbsp; Library</a>
-        <a class="list-group-item" href="#"><i class="fa fa-pencil fa-fw" aria-hidde="true"></i>&nbsp; Applications</a>
-        <a class="list-group-item" href="#"><i class="fa fa-cog fa-fw" aria-hidde="true"></i>&nbsp; Settings</a>
+        <a class="list-group-item" href="#"><i class="fa fa-home fa-fw" aria-hidden="true"></i>&nbsp; Home</a>
+        <a class="list-group-item" href="#"><i class="fa fa-book fa-fw" aria-hidden="true"></i>&nbsp; Library</a>
+        <a class="list-group-item" href="#"><i class="fa fa-pencil fa-fw" aria-hidden="true"></i>&nbsp; Applications</a>
+        <a class="list-group-item" href="#"><i class="fa fa-cog fa-fw" aria-hidden="true"></i>&nbsp; Settings</a>
       </div>
     </div>
     <div class="col-md-9 col-sm-8">