Add CHANGELOG

Author: znichollscr

docs/changelog.md

@@ -0,0 +1,23 @@
+# Changelog
+
+Versions follow [Semantic Versioning](https://semver.org/) (`<major>.<minor>.<patch>`).
+
+Backward incompatible (breaking) changes will only be introduced in major versions
+with advance notice in the **Deprecations** section of releases.
+
+<!--
+You should *NOT* be adding new changelog entries to this file,
+this file is managed by towncrier.
+See `changelog/README.md`.
+
+You *may* edit previous changelogs to fix problems like typo corrections or such.
+To add a new changelog entry, please see
+`changelog/README.md`
+and https://pip.pypa.io/en/latest/development/contributing/#news-entries,
+noting that we use the `changelog` directory instead of news,
+markdown instead of restructured text and use slightly different categories
+from the examples given in that link.
+-->
+
+<!-- towncrier release notes start -->
+