message: Update the TFLM CI docs based on the new way to build a docker image.
diff: +<!-- mdformat off(b/169948621#comment2) -->
  +
  <!--
  Semi-automated TOC generation with instructions from
  https://github.com/ekalinin/github-markdown-toc#auto-insert-and-update-toc
  @@ -314,24 +316,35 @@ that can be expanded and improved as necessary.
  [![TfLite Micro Build](docs/images/tflm_continuous_integration_1.png)](https://storage.googleapis.com/tensorflow-kokoro-build-badges/tflite-micro.html)
  - * Most of the tests that are run as part of the CI are with the
  +* Tests that are run as part of the CI are with the
  [micro/tools/ci_build/test_all.sh](https://github.com/tensorflow/tensorflow/blob/master/tensorflow/lite/micro/tools/ci_build/test_all.sh)
  - script.
  -
  - * There are a few additional tests that use bazel that are not
  - captured by the `test_all.sh` script.
  + script when run with the `GITHUB_PRESUBMIT` command line parameter:
  + ```
  + tensorflow/lite/micro/tools/ci_build/test_all.sh GITHUB_PRESUBMIT
  + ```
  * If an error is not reproducible on your development machine, you can
  - recreate the docker container that is used on the CI servers with the
  - following commands (run from the root of the tensorflow github repo):
  + recreate the docker container that is used on the CI servers.
  + * First, create a build a TFLM docker image with:
  ```
  - mkdir /tmp/tflm-docker
  - docker build -f tensorflow/tools/ci_build/Dockerfile.micro -t tflm /tmp/tflm-docker
  - docker run -v `pwd`:/tensorflow -it tflm bash
  + tensorflow/tools/ci_build/ci_build.sh micro bash
  ```
  + The second parameter to the ci_build.sh script is not important. It can
  + be any command.
  - The `docker run` command is mounting the tensorflow repository on your
  - machine to the docker containter. As a result, any changes made within the
  - docker container will also be reflected in the directory in the host
  - machine.
  + * Next, mount the tensorflow repo on your machine to the docker container.
  + Please be careful (or make a separate clone of tensorflow) since any
  + changes docker container will also be reflected in the directory in the
  + host machine.
  + ```
  + docker run -v `pwd`:/tensorflow -it tf_ci.micro bash
  + ```
  +
  + * Within the docker container, you can now run the TFLM test script, or
  + any other command that you would like to test. For example, the following
  + commands will run all of the TFLM checks:
  + ```
  + # cd tensorflow
  + # tensorflow/lite/micro/tools/ci_build/test_all.sh GITHUB_PRESUBMIT
  + ```
  