Remove scripts/pre-commit.sh (#2067)

* Update dev.md

* Remove scripts/pre-commit.hs

Author: wangkuiyi

docs/tutorials/dev.md

@@ -24,13 +24,13 @@ container and bind mount the local Git repo into the container.  In this
 container, we run the pre-commit command.
 
 ```bash
-docker run --rm -it -v $PWD:/work -w /work \
-  elasticdl:dev /work/scripts/pre-commit.sh
+docker run --rm -it -v $PWD:/work -w /work elasticdl:dev
+  bash -c "make -f elasticdl/Makefile && pre-commit run -a"
 ```
 
 If you have all required tools installed, you can run the same script on your
 host.
 
 ```bash
-./scripts/pre-commit.sh
+make -f elasticdl/Makefile && pre-commit run -a
 ```