Typo in README

To correct the hyperlink and make aaron_s_hawley happy :).

Author: xnning

README.md

@@ -12,7 +12,7 @@ API documentation is available [here](http://www.scala-lang.org/api/current/scal
 
 ## Maintenance status
 
-This library is community-maintained. The lead maintainers are [@biswanaths](https://github.com/biswanaths) and [@aaron_s_hawley][https://github.com/ashawley].
+This library is community-maintained. The lead maintainers are [@biswanaths](https://github.com/biswanaths) and [@aaron_s_hawley](https://github.com/ashawley).
 
 ## Security best practices