update changelog

Author: duaraghav8

CHANGELOG.md

@@ -1,6 +1,6 @@
 # Changelog
 
-## 1.2.3 ()
+## 1.2.3 (2019-02-11)
 - Added support for `solium-disable-previous-line` comment directive.
 - Added support for `solium-enable` comment directive. See [configuring with comments](https://ethlint.readthedocs.io/en/latest/user-guide.html#configuring-with-comments). This feature currently has a limitation which has been documented in [Known Issues](https://ethlint.readthedocs.io/en/latest/known-issues.html).
 - Added Pull Request template.