Make global delete button more explicit.

Author: blueimp

index.html

@@ -141,7 +141,7 @@ <h1>jQuery File Upload Demo</h1>
             </button>
             <button type="button" class="btn btn-danger delete">
               <i class="glyphicon glyphicon-trash"></i>
-              <span>Delete</span>
+              <span>Delete selected</span>
             </button>
             <input type="checkbox" class="toggle" />
             <!-- The global file processing state -->