message: docs: fix docker image name
  Use the full name `nervos/ckb`.
diff: Start latest CKB release with default configuration:
  ```bash
  -docker run -it ckb:latest run
  +docker run -it nervos/ckb:latest run
  ```
  +See other
  +[tags](https://cloud.docker.com/u/nervos/repository/docker/nervos/ckb/tags)
  +listed in DockerHub.
  +
  +- Tag `latest` is always the latest release, which is built from the latest
  + master branch.
  +- Tag `develop` is built from the latest develop branch.
  +- Tags `vx.y.z` are history releases.
  +- Tags `vx.y.z-rc` are the preview of the release candidates.
  +
  It is recommended to mount a volume at `/var/lib/ckb` in the container.
  Following is an example to mount a volume, generate config files in the volume
  and start CKB from it. The example will use a local directory as the volume.
  @@ -21,7 +31,7 @@ Then init the directory with testnet chain spec.
  ```bash
  docker run --rm -it \
  -v "$(pwd)/ckb-testnet:/var/lib/ckb" \
  - ckb:latest init --spec testnet
  + nervos/ckb:latest init --spec testnet
  ```
  Check the directory `ckb-testnet`. It should contains two config files now:
  @@ -32,7 +42,7 @@ Edit the files if you like, then start a node from the volume:
  ```bash
  docker run -it
  -v "$(pwd)/ckb-testnet:/var/lib/ckb" \
  - ckb:latest run
  + nervos/ckb:latest run
  ```
  You can also start a miner with the following command. But you have to publish
  @@ -42,5 +52,5 @@ connect to the node.
  ```bash
  docker run -it
  -v "$(pwd)/ckb-testnet:/var/lib/ckb" \
  - ckb:latest miner
  + nervos/ckb:latest miner
  ```
  