Added changelog.md file

Author: grogy

CHANGELOG.md

@@ -0,0 +1,26 @@
+# Changelog
+
+All notable changes to this project will be documented in this file.
+
+The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
+
+## [Unreleased]
+
+### Added
+
+- Added changelog.
+
+### Fixed
+
+- Fixed vendor location for running from other folder from [@Erkens](https://github.com/Erkens).
+
+### Internal
+
+- Added a .gitattributes file from [@jrfnl](https://github.com/jrfnl), thanks for issue to [@ondrejmirtes](https://github.com/ondrejmirtes).
+- Fixed incorrect unit tests from [@jrfnl](https://github.com/jrfnl).
+- Fixed minor grammatical errors from [@jrfnl](https://github.com/jrfnl).
+- Added Travis: test against nightly (= PHP 8) from [@jrfnl](https://github.com/jrfnl).
+- Travis: removed sudo from [@jrfnl](https://github.com/jrfnl).
+- Added info about installing like not a dependency.
+- Cleaned readme - new organization from previous package.
+- Added checklist for new version from [@szepeviktor](https://github.com/szepeviktor).

doc/new-release.md

@@ -1,5 +1,11 @@
 # Checklist for new release
 
 1. change version in `src/Application.php`
-2. add new Git tag
-3. create [new release on GitHub](https://github.com/php-parallel-lint/PHP-Parallel-Lint/releases) with summary of important changes with respect to last version
+2. change version and date in `CHANGELOG.md`
+3. add new Git tag
+4. create [new release on GitHub](https://github.com/php-parallel-lint/PHP-Parallel-Lint/releases) with summary of important changes with respect to last version
+5. to Github release add diff link, e.g.
+
+```
+For the details you can have a look at the [diff](https://github.com/php-parallel-lint/PHP-Parallel-Lint/compare/v1.0.0...v1.1.0).
+```