Update CHANGELOG.md

Author: YaokaiYang-assaultmaster

CHANGELOG.md

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+# Changelog
 
+Versions are monotonically increased based on Semantic Versioning.
+
+***
+
+## V0.2 (09/12/2017)
+
+## Backward incompatible changes
+None
+
+## Deprecations
+None
+
+## Changes
+Fixed [issue #1](https://github.com/YaokaiYang-assaultmaster/PythonPortScanner/issues/1). Specifically, fixed Windows has no `SO_REUSEPORT` for TCP socket error and change message encoding to `utf-8` before sending out. 
+
+***
+
+## V0.1 (05/30/2017)
+
+## Backward incompatible changes
+None
+
+## Deprecations
+None
+
+## Changes
+Initialized the whole project. First version finished.