Fix for icon-material.html - Wrong hint for usage

Changed the class names from mid to mdi in usage phrase

pages/icon-material.html

@@ -461,7 +461,7 @@
                             <div class="card">
                                 <div class="card-header">
                                     <h4 class="card-title">Material Icons</h4>
-                                    <h6 class="card-subtitle">you can use any icon with class of <code class="m-r-10">mid mid-</code>name of icon</h6>
+                                    <h6 class="card-subtitle">you can use any icon with class of <code class="m-r-10">mdi mdi-</code>name of icon</h6>
                                 </div>
                                 <div class="card-body">
                                     <div class="material-icon-list-demo">
@@ -2347,4 +2347,4 @@
     <script src="../assets/libs/js/main-js.js"></script>
 </body>
  
-</html>
+</html>