Improve readme about custom buttons.

Readme.md

@@ -250,13 +250,14 @@ var socialLikesButtons = {
 };
 ```
 
-If you know the social network search page's URL, you can make a link to results of searching in this network. There are search URLs for Twitter and VKontakte by default.
+Or with a custom click handler:
 
 ```javascript
 var socialLikesButtons = {
-	twitter: {
-		...
-		searchUrl: 'https://twitter.com/search?src=typd&q={url}'
+	livejournal: {
+		click: function(e) {
+			// this.widget.data('something')
+		}
 	}
 };
 ```