Extend a clean target

Makefile

@@ -5,5 +5,13 @@ lint:
 isort:
 	isort -rc ./platformio
 
-clean:
-	find . -name \*.pyc -delete
+clean-docs:
+	rm -rf docs/_build
+
+clean: clean-docs
+	find . -name \*.pyc -delete
+	find . -name __pycache__ -delete
+	rm -rf .cache
+	rm -rf build
+	rm -rf htmlcov
+	rm -f .coverage