Update README.md

Author: nitinjs

README.md

@@ -1,2 +1,21 @@
 # jquery-duplicatewindow
 Not allow user to open website in multiple windows 
+
+jQuery plugin to check if current window is duplicate window,<br/>
+I createdd this plugin based on timkellypa's answer on stackoverflow<br/>
+"Stop people having my website loaded on multiple tabs"<br/>
+<a href="https://stackoverflow.com/a/45717724/223752">https://stackoverflow.com/a/45717724/223752</a><br/>
+<br/>
+This plugin works across all browsers IE, Firefox, Microsoft Edge & Google chrome<br/>
+<br/>
+It is basically checking GUID of the window against value in cookie<br/>
+
+Sample usage:
+    <script type="text/javascript">
+        $(document).ready(function () {
+            if (window.IsDuplicate()) {
+                alert("this is duplicate window\n\n closing...");
+                window.close();
+            }
+        });
+    </script>