demos/dialog/modal.html: clarified the description for modal

demos/dialog/modal.html

@@ -48,11 +48,15 @@
 
 </div><!-- End demo -->
 
-
-
 <div class="demo-description">
 
-<p>This is identical to the default dialog except a semi-transparent overlay layer is added as an option to make this look more modal and dim out the page content behind it to bring the user's attention to the dialog.</p><p>The dialog window can be moved, resized and closed with the 'x' icon.</p>
+<p>
+This is a simple modal dialog with a semi-transparent overlay layer added as an option to dim out the page content behind it and bring the user's attention to the dialog. A modal dialog prevents interaction from the rest of the page until it is dismissed.
+</p>
+
+<p>
+The dialog window can be moved, resized and closed with the 'x' icon.
+</p>
 
 </div><!-- End demo-description -->