docs(release): add release doc with changelog generation section

Author: njhale

Documentation/design/release.md

@@ -0,0 +1,8 @@
+# Changelog Generation
+
+Changelogs for OLM are generated using [GitHub Changelog Generator](https://github.com/github-changelog-generator/github-changelog-generator).
+
+```bash
+github_changelog_generator -u operator-framework -p operator-lifecycle-manager --since-tag=<start-semver> \
+    --token=<github-api-token> --future-release=<end-semver> --pr-label="**Other changes:**"
+```