[skip ci] update changelog

CHANGELOG.md

@@ -1,6 +1,21 @@
-- INTERNAL
-  - migrate to thegeeklab namespace
-  - add markdown linting to CI (markdownlint-cli)
-  - add spellchecking to CI (spellcheck-cli)
-  - add broken link check to CI (broken-link-checker)
-  - upgrade CI pipeline to use Hugo v0.74.3
+# Changelog
+
+## v0.2.0 (2021-01-03)
+
+### Docs
+
+- add contributing information
+
+### Build
+
+- migrate to poetry
+
+### Others
+
+- use renovate preset config
+- replace master by main as default branch
+
+### Breaking Changes
+
+- drop Python 2.7 support
+- drop Python 3.5 support