message: Update the Vue.js readme
  This is a minor update preparing the Vue.js readme for use in
  airbrake-docs.
  Decrease the header size for consistency with airbrake-docs
  Increase the verbosity of the configuration instructions
diff: -# Vue.js error handler
  +### Vue.js error handler
  -You need to define error handler:
  +You can start reporting errors from your Vue.js app by configuring an
  +[`errorHandler`](https://vuejs.org/v2/api/#errorHandler) that uses an
  +`AirbrakeClient` initialized with your `projectId` and `projectKey`.
  ```js
  import AirbrakeClient from 'airbrake-js';
  @@ -18,4 +20,5 @@ Vue.config.errorHandler = function (err, vm, info) {
  }
  ```
  -Read [errorHandler documentation](https://vuejs.org/v2/api/#errorHandler) for more details.
  +For more information on Vue.js error handling, read the [`errorHandler`
  +documentation](https://vuejs.org/v2/api/#errorHandler).
  