message: add docker CLI to readme
diff: @@ -9,6 +9,24 @@ From the v3.0 release, we stop releasing the HugeCTR container separately. Inste
  You may want to use the Merlin NGC container for both research and production purposes. But if you want to build a container from the dockerfile by yourself, please refer to the following content.
  +## Docker CLI Quick Reference
  +```
  +$ docker build [<opts>] <path> | <URL>
  + Build a new image from the source code at PATH
  + -f, --file path/to/Dockerfile
  + Path to the Dockerfile to use. Default: Dockerfile.
  + --build-arg <varname>=<value>
  + Name and value of a build argument defined with ARG
  + Dockerfile instruction
  + -t "<name>[:<tag>]"
  + Repository names (and optionally with tags) to be applied
  + to the resulting image
  + --label =<label>
  + Set metadata for an image
  + -q, --quiet Suppress the output generated by containers
  + --rm Remove intermediate containers after a successful build
  +```
  +
  ## Build Container for Model Training
  The `Dockerfile.train` supports two build mode: `devel` and `release`,
  @@ -26,7 +44,7 @@ Under the current directory, you can build the container by
  ```
  docker build -t hugectr:devel -f Dockerfile.train .
  ```
  -
  +Please refer to [Docker CLI Quick Reference](#docker-cli-quick-reference) for the description of options.
  ## Build Container for Inference
  