message: Fix warning in the React example component
  The example was producing a warning that `Component` is imported but never used.
diff: @@ -5,7 +5,7 @@ To report errors from a React app, you'll need to set up and use an
  and initialize a `Notifier` with your `projectId` and `projectKey`.
  ```js
  -import React, { Component } from 'react';
  +import React from 'react';
  import { Notifier } from '@airbrake/browser';
  class ErrorBoundary extends React.Component {
  