Added screenshot

Author: bluezed

README.md

@@ -5,7 +5,6 @@ It uses a glyphicon, some CSS and the .animate jQuery function. All these are pa
 
 Installation
 ------------
-
 The preferred way to install this extension is through [composer](http://getcomposer.org/download/).
 
 Either run
@@ -25,7 +24,6 @@ to the require section of your `composer.json` file.
 
 How to use
 ----------
-
 Add this line to your main layout so the widget gets loaded automatically into every page.
 ```php
 <?= \bluezed\scrollTop\ScrollTop::widget() ?>
@@ -35,3 +33,8 @@ By default your main layout should be located here:
 ```
 <Project-Folder>/views/layouts/main.php
 ```
+
+Screenshot
+----------
+The button appears in the bottom right corner of the page once you have scrolled down at least 150px.
+![Screenshot of the button](http://s19.postimg.org/dkro8azxf/Scroll_Top_Button.png)