message: Update README for micro speech ESP example.
  Imported from GitHub PR
diff: @@ -17,6 +17,7 @@ kilobytes of Flash.
  - [Getting started](#getting-started)
  - [Deploy to Arduino](#deploy-to-arduino)
  +- [Deploy to ESP32](#deploy-to-esp32)
  - [Deploy to SparkFun Edge](#deploy-to-sparkfun-edge)
  - [Deploy to STM32F746](#deploy-to-STM32F746)
  - [Deploy to NXP FRDM K66F](#deploy-to-nxp-frdm-k66f)
  @@ -94,7 +95,11 @@ The sample has been tested on ESP-IDF version 4.0 with the following devices: -
  ESP-EYE is a board which has a built-in microphone which can be used to run this
  example , if you want to use other esp boards you will have to connect
  -microphone externally and write your own +audio_provider.cc+.
  +microphone externally and write your own
  +[audio_provider.cc](https://github.com/tensorflow/tensorflow/tree/master/tensorflow/lite/micro/examples/micro_speech/esp/audio_provider.cc).
  +You can also edit the
  +[command_responder.cc](https://github.com/tensorflow/tensorflow/tree/master/tensorflow/lite/micro/examples/micro_speech/command_responder.cc)
  +to define your own actions after detecting command.
  ### Install the ESP IDF
  