[DEV] Regen function doc strings on make docs (#977)

* [DEV] Regen docs with `make docs`

* default 0

Makefile

@@ -40,6 +40,7 @@ executable: clean
 	pyinstaller ytdl-sub.spec
 	mv dist/ytdl-sub dist/ytdl-sub${EXEC_SUFFIX}
 docs:
+	REGENERATE_DOCS=1 pytest tests/unit/docgen/test_docgen.py
 	sphinx-build -M html docs/source/ docs/build/
 clean:
 	rm -rf \

tools/docgen/docgen.py

@@ -1,7 +1,8 @@
+import os
 from abc import abstractmethod
 from pathlib import Path
 
-REGENERATE_DOCS: bool = False
+REGENERATE_DOCS: bool = bool(os.environ.get("REGENERATE_DOCS", 0))
 
 
 class DocGen: