update clean script

Author: HillLiu

clean.sh

@@ -1,6 +1,5 @@
 #!/bin/sh
 find ./vendor -type d | xargs rm -rf
 find ./.git -type d | xargs rm -rf
-find ./demo -type d | xargs rm -rf
 find ./composer.lock | xargs rm -rf
 find ./clean.sh | xargs rm -rf