Allow custom filenames for changelog command

docs/tools.md

@@ -69,3 +69,11 @@ basic commands:
 
 If a [pytest](https://docs.pytest.org/en/stable/) configuration file is found, a
 `test` command will be exposed that runs `pytest`.
+
+## changelog (github)
+
+`changelog` command will produce a `CHANGELOG.md` file based on Github Releases.
+You can define `CHANGELOG_FILE` environment variable to make it generate the
+file in a different location.
+
+This command is available only when `gh` command line utility is installed.

src/mk/tools/pre.py

@@ -55,7 +55,8 @@ def changelog(self) -> None:
         result = result.rstrip("\r\n") + "\n"
         result = result.replace("\r\n", "\n")
         result = re.sub(r"\n{3,}", "\n\n", result, re.MULTILINE)
-        with open("CHANGELOG.md", "w", encoding="utf-8") as f:
+        filename = os.environ.get("CHANGELOG_FILE", "CHANGELOG.md")
+        with open(filename, "w", encoding="utf-8") as f:
             f.write(result)
             logging.info("Wrote CHANGELOG.md")