Add doc

src/views/dialog/DialogDoc.vue

@@ -56,6 +56,14 @@ export default {
 <Dialog position="top" :visible.sync="display">
 	Content
 </Dialog>
+</CodeHighlight>
+
+                <h3>Popup Content inside the Dialog</h3>
+                <p>If the dialog contains components with popup elements such as Dropdown or Calendar, set <i>contentStyle</i> to overflow:visible so that overlays can be displayed outside of the content area.</p>
+<CodeHighlight>
+&lt;Dialog :visible.sync="display" :contentStyle="{overflow: 'visible'}"&gt;
+	Content
+&lt;/Dialog&gt;
 </CodeHighlight>
 
 				<h3>Properties</h3>