Add tailRec demo to the README

Author: ajnsit

README.md

@@ -75,3 +75,4 @@ Individual example sources -
 10. Asynchronous timers which can be cancelled. [Source](https://github.com/ajnsit/purescript-concur/blob/master/examples/Test/Timers.purs).
 11. A routed widget which demonstrates routing. [Source](https://github.com/ajnsit/purescript-concur/blob/master/examples/Test/Routing.purs).
 12. Performance test - A huge list of 50 thousand parallel buttons. This has two variants, fast (uses slightly lower level interface) and slow (idiomatic concur code). [Source](https://github.com/ajnsit/purescript-concur/blob/master/examples/Test/SlowButtonList.purs).
+13. Tail Recursion demo - Since Concur is purely functional in nature, its primary mode of iteration is via recursion. Purescript in general is NOT stack stafe with tail recursion; It uses tricks like tailRec and tailRecM. However, Concur performs trampolining to make monadic recursion completely stack safe. This example demonstrates that by making a huge number of tail recursive calls in a short span of time. [Source](https://github.com/ajnsit/purescript-concur/blob/master/examples/Test/TailRec.purs).