update docs copy to include mention of info alert messages

docs/index.html

@@ -1602,7 +1602,7 @@
 ================================================== -->
 <section id="alerts">
   <div class="page-header">
-    <h1>Alerts &amp; Errors <small>Styles for success, warning, and error messages or alerts</small></h1>
+    <h1>Alerts &amp; Errors <small>Styles for success, warning, error, and info messages</small></h1>
   </div>
   <!-- Basic alert messages -->
   <div class="row">