code: function hooks(compiler, options) {
    return Promise.resolve()
      .then(() => require('./HmrServer'))
      .then(({ default: HmrServer }) =>
        new HmrServer({
          ...options,
          compiler, // webpack compiler
        }).run()
      );
  }
docs: Add compiler hooks and start watching (through compiler) for changes.
  @returns {Promise.<HmrServer>}