Updated changelog

CHANGELOG.md

 # Release Notes
 
-## [Unreleased]
+## v5.4.23 (2017-05-11)
+
+### Added
+- Added SQL Server connection ([#4253](https://github.com/laravel/laravel/pull/4253), [#4254](https://github.com/laravel/laravel/pull/4254))
+
+### Changed
+- Switch to using meta
+- Use CSRF token from `meta` tag, instead of `window.Laravel` object ([#4260](https://github.com/laravel/laravel/pull/4260))
+- Log console error if CSRF token cannot be found ([1155245](https://github.com/laravel/laravel/commit/1155245a596113dc2cd0e9083603fa11df2eacd9))
+
+### Fixed
+- Added missing `ipv4` and `ipv6` validation messages ([#4261](https://github.com/laravel/laravel/pull/4261))
+
+
+## v5.4.21 (2017-04-28)
+
+### Added
+- Added `FILESYSTEM_DRIVER` and `FILESYSTEM_CLOUD` environment variables ([#4236](https://github.com/laravel/laravel/pull/4236))
+
+### Changed
+- Use lowercase doctype ([#4241](https://github.com/laravel/laravel/pull/4241))
+
+
+## v5.4.19 (2017-04-20)
 
 ### Added
 - Added `optimize-autoloader` to `config` in `composer.json` ([#4189](https://github.com/laravel/laravel/pull/4189))