Move full changelog to docs/changelog.md, add a summary in README

bin/update_readme_changelog.py

@@ -0,0 +1,47 @@
+#!/usr/bin/env python3
+
+import re
+import sys
+from pathlib import Path
+
+PROJECT_ROOT = Path(__file__).parent / ".."
+CHANGELOG_FILE = PROJECT_ROOT / "docs" / "changelog.md"
+README_FILE = PROJECT_ROOT / "README.md"
+
+# https://regexr.com/622ds
+FIRST_5_CHANGELOG_ENTRIES_REGEX = re.compile(r"""(^###.*?(?=###)){5}""", re.DOTALL | re.MULTILINE)
+
+# https://regexr.com/622e5
+README_CHANGELOG_SECTION = re.compile(
+    r"""(?<=<!-- START bin\/update_readme_changelog.py -->\n).*(?=<!-- END bin\/update_readme_changelog.py -->)""",
+    re.DOTALL,
+)
+
+
+def main():
+    changelog_text = CHANGELOG_FILE.read_text()
+    readme_text = README_FILE.read_text()
+
+    mini_changelog_match = FIRST_5_CHANGELOG_ENTRIES_REGEX.search(changelog_text)
+    assert mini_changelog_match, "Failed to find the first few changelog entries"
+
+    mini_changelog = "\n".join(
+        [
+            "",
+            "<!-- this section was generated by bin/update_readme_changelog.py -- do not edit manually -->",
+            "",
+            mini_changelog_match.group(0).strip(),
+            "",
+            "",
+        ]
+    )
+
+    if not re.search(README_CHANGELOG_SECTION, readme_text):
+        sys.exit("Changelog section not found in README")
+
+    readme_text = re.sub(README_CHANGELOG_SECTION, mini_changelog, readme_text)
+    README_FILE.write_text(readme_text)
+
+
+if __name__ == "__main__":
+    main()