Add CHANGELOG

Author: dcsg

CHANGELOG.md

@@ -0,0 +1,27 @@
+# Changelog
+
+All notable changes to `Immutable Collections for PHP` will be documented in this file.
+
+Updates should follow the [Keep a CHANGELOG](http://keepachangelog.com/) principles.
+
+
+## 1.1.1 - 2019-01-27
+
+### Added
+- Tests namespace to the `autoload_dev`
+
+### Removed
+- Tests namespaces from the `autoload`
+
+## 1.1.0 - 2019-01-27
+
+### Added
+- declared strict types in all PHP files.
+
+
+## 1.0.0 - 2019-01-26 [Initial Release]
+
+### Added
+- The [Immutable List Collection](https://github.com/dcsg/php-immutable-collections/blob/master/src/ImmutableCollection.php) and [Immutable Set Collection](https://github.com/dcsg/php-immutable-collections/blob/master/src/SetImmutableCollection.php)
+- Unit tests
+- Examples