add --rm for make docker, [MyBad]

Author: PanQL

Makefile

@@ -12,7 +12,7 @@ clean:
 env:
 	make -C os env
 docker:
-	docker run -it --mount type=bind,source=$(shell pwd),destination=/mnt ${DOCKER_NAME}
+	docker run --rm -it --mount type=bind,source=$(shell pwd),destination=/mnt ${DOCKER_NAME}
 
 build_docker: qemu-4.1.1.tar.xz riscv64-unknown-elf-gcc-8.3.0-2019.08.0-x86_64-linux-ubuntu14.tar.gz
 	docker build -t ${DOCKER_NAME} .