Add changelog

Author: laurynas

CHANGELOG.md

@@ -0,0 +1,14 @@
+# 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/1.1.0/),
+and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
+
+
+## v2.0.0
+
+### Changed
+- Switched to v3 API which uses updated language detection model
+- ⚠️ Added `DetectResult` field `score`, removed `confidence` and `reliable`
+- Renamed `GetUserStatusAsync` to `GetAccountStatusAsync`

README.md

@@ -35,6 +35,10 @@ From within Visual Studio:
 5. Click on the DetectLanguage package, select the appropriate version in the
    right-tab and click *Install*.
 
+### Upgrading
+
+When upgrading please check [changelog](CHANGELOG.md) for breaking changes.
+
 ## Documentation
 
 For a comprehensive list of examples, check out the [API documentation][api-docs].