chore(Makefile): update release and clean command (#47)

diff --git a/Makefile b/Makefile
index 6f28d41..eedfded 100644
--- a/Makefile
+++ b/Makefile
@@ -43,7 +43,7 @@
 
 .PHONY: clean
 clean:
-	rm -rf apache_apisix.egg-info dist build assets .coverage report.html
+	rm -rf apache_apisix.egg-info dist build assets .coverage report.html release
 	find . -name "__pycache__" -exec rm -r {} +
 	find . -name ".pytest_cache" -exec rm -r {} +
 	find . -name "*.pyc" -exec rm -r {} +
@@ -56,7 +56,8 @@
 
 .PHONY: release
 release:
-	tar -zcvf $(RELEASE_SRC).tgz apisix docs tests *.md LICENSE Makefile NOTICE pytest.ini requirements.txt setup.py
+	tar -zcvf $(RELEASE_SRC).tgz apisix bin docs tests conf setup.py *.md \
+ 	LICENSE Makefile NOTICE pytest.ini requirements.txt
 	gpg --batch --yes --armor --detach-sig $(RELEASE_SRC).tgz
 	shasum -a 512 $(RELEASE_SRC).tgz > $(RELEASE_SRC).tgz.sha512
 	mkdir -p release