Add warning about website unmaintained

Author: mrego

index.html

@@ -38,6 +38,11 @@ <h1>CSS Grid Layout Examples</h1>
         </div>
 
         <div class="container">
+            <div class="row">
+                <div class="col-md-12">
+                    <div class="alert alert-danger"><span class="label label-danger">Deprecated</span> This website hasn't been maintained for a while, information can be oudated.</div>
+                </div>
+            </div>
             <div class="row">
                 <div class="col-md-4">
                     <div class="panel panel-default">