Add build guide.

Makefile

@@ -168,7 +168,7 @@ docker_build:
 	@docker build docker/ -t $(docker_image):$(tag)
 
 docker_iso:
-	docker run --rm $(docker_args) $(docker_image):$(tag) make iso
+	@docker run --rm $(docker_args) $(docker_image):$(tag) make iso
 
 docker_run: docker_iso
 	@qemu-system-$(arch) -cdrom $(iso) -s
@@ -180,4 +180,4 @@ docker_clean:
 	@docker volume rm $(docker_clean_args)
 
 docker_riscv:
-	@docker run -it --rm $(docker_args) riscv-rust
+	@docker run -it --rm $(docker_args) wangrunji0408/riscv-rust

README.md

@@ -1,13 +1,31 @@
-# RustOS for x86_64 SMP
+# RustOS
 
 ## Port to RISCV (WIP)
 
-2018年计算机系统综合实验
+2018年THU计算机系统综合实验
 
 [Project Wiki](http://os.cs.tsinghua.edu.cn/oscourse/csproject2018/group05)
 
 [Documents](./docs/RISCV.md)
 
+### Environment
+
+[Dockerfile](./riscv-env/Dockerfile) (Can not build directly. Just for reference)
+
+Available on DockerHub: `wangrunji0408/riscv-rust`
+
+### How to run
+
+```bash
+git clone https://github.com/wangrunji0408/RustOS.git -b riscv --recursive
+cd RustOS
+# Pull docker image and enter docker interactive shell
+make docker_riscv
+# Inside docker ...
+make build
+make justrun
+```
+
 ## Summary
 
 [![Build Status](https://travis-ci.org/wangrunji0408/RustOS.svg?branch=master)](https://travis-ci.org/wangrunji0408/RustOS)