Update the CHANGELOG

Author: stouset

sudo_plugin/CHANGELOG.md

@@ -16,6 +16,9 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - Allows plugins to use any error library they wish, as long as the error
   types returned in `Result`s implement `Into<sudo_plugin::errors::Error>`.
 
+### Fixed
+- `change_winsize` should return a `c_int`.
+
 ## [1.1.0] - 2018-05-18
 
 ### Added