Add license information to readme

README.md

 # bussard
 
-# Bussard
-## An RSS reader
+# Bussard
+## An RSS reader
+
+<a rel="license" href="http://creativecommons.org/licenses/by-sa/4.0/"><img alt="Creative Commons License" style="border-width:0" src="https://i.creativecommons.org/l/by-sa/4.0/88x31.png" /></a><br />This work is licensed under a <a rel="license" href="http://creativecommons.org/licenses/by-sa/4.0/">Creative Commons Attribution-ShareAlike 4.0 International License</a>. This means:
+
+* You may use this code, or any portion of it, in your own works. 
+* If you do so, you MUST:
+* * Give credit to the original author.
+* * Make the source code of the work that incorporates this code freely available.
+* If you do so, you MAY:
+* * Make your project commercially available (i.e. charge money for it).