added google play link

Author: donfuxx

README.md

@@ -9,3 +9,5 @@ Usage:
 2. In the chooser select "Sharemarks" to share the bookmark with this app.
 3. The shared bookmark appears in the list. On click on the shared bookmark the link will be opened.
 4. Swipe left to delete the bookmark. Swipe right or long click to share it.
+
+The app can be downloaded at Google Play: https://play.google.com/store/apps/details?id=com.appham.sharemarks