Bug 1703818: Update HISTORY.rst to CHANGELOG.md (#306)

Author: mdboom

.github/pull_request_template.md

@@ -4,5 +4,5 @@
   - `make test` runs without emitting any warnings
   - `make lint` runs without emitting any errors
 - [ ] **Tests**: This PR includes thorough tests or an explanation of why it does not
-- [ ] **Changelog**: This PR includes a changelog entry to `HISTORY.rst` or an explanation of why it does not need one
+- [ ] **Changelog**: This PR includes a changelog entry to `CHANGELOG.md` or an explanation of why it does not need one
   - Any breaking changes to language binding APIs are noted explicitly