Adding paypal link

README.md

@@ -16,6 +16,12 @@
 
 ---
 
+If you like to see this project grow, your donation of any amount is much appreciated.
+
+[![Donate](https://www.paypalobjects.com/en_US/i/btn/btn_donate_SM.gif)](https://www.paypal.com/cgi-bin/webscr?cmd=_s-xclick&hosted_button_id=FSFYYNEQ8RKWU)
+
+---
+
 This is a fast, pure-ruby implementation of an activity feed concept commonly used in social networking applications. The implementation is optimized for **read-time performance** and high concurrency (lots of users), and can be extended with custom backend providers. Two providers come bundled: the production-ready Redis provider, and a naive pure Hash-based provider.
 
 __Important Notes and Acknowledgements:__