Adds CHANGELOG entry for #232

Author: weierophinney

CHANGELOG.md

@@ -22,6 +22,8 @@ All notable changes to this project will be documented in this file, in reverse
 
 ### Fixed
 
+- [#232](https://github.com/zendframework/zend-validator/pull/232) updates the `Hostname` validator to allow underscores in subdomains.
+
 - [#218](https://github.com/zendframework/zend-validator/pull/218) fixes a precision issue with the `Step` validator.
 
 ## 2.10.2 - 2018-02-01