README: Remove mention of boost::asio

Not used anymore

Author: jonnor

README.md

@@ -6,7 +6,7 @@ runtime. It integrates with other FBP tools like the [Flowhub](http://flowhub.io
 This library makes it easy to create MsgFlo participants in C++.
 
 msgflo-cpp is written in C++11 and is built on top of [AMQP-CPP](https://github.com/CopernicaMarketingSoftware/AMQP-CPP),
-[boost::asio](http://www.boost.org/doc/libs/1_55_0/doc/html/boost_asio.html) and [json11](https://github.com/dropbox/json11).
+and [json11](https://github.com/dropbox/json11).
 
 ## Status