message: Update READMEs
  Expand documentation, fix grammar and spelling errors, and general clean
  up.
diff: -# Airbrake error notifier for JavaScript
  +# Official Airbrake Notifiers for JavaScript
  [![Build Status](https://github.com/airbrake/airbrake-js/workflows/CI/badge.svg?branch=master)](https://github.com/airbrake/airbrake-js/actions?query=branch%3Amaster)
  Please choose one of the following packages:
  -- [@airbrake/browser](packages/browser) for web browsers,
  -- [@airbrake/node](packages/node) for Node.js.
  +
  +[@airbrake/browser](packages/browser) for web browsers.
  +
  +[@airbrake/node](packages/node) for Node.js.
  