message: docs: Include information about fatalError install callback
diff: @@ -6,10 +6,20 @@ To get started, you need to configure Raven to use your Sentry DSN:
  .. sourcecode:: javascript
  var Raven = require('raven');
  - Raven.config('___PUBLIC_DSN___').install()
  + Raven.config('___PUBLIC_DSN___').install();
  At this point, Raven is ready to capture any uncaught exceptions.
  +Note that the ``install`` method can optionally take a callback function that is invoked if a fatal, non-recoverable error occurs.
  +You can use this callback to perform any cleanup that should occur before the Node process exits.
  +
  +.. sourcecode:: javascript
  +
  + Raven.config('___PUBLIC_DSN___').install(function (err, initialErr, eventId) {
  + console.error(err);
  + process.exit(1);
  + });
  +
  Optional settings
  -----------------
  @@ -19,7 +29,7 @@ Optional settings
  Raven.config('___PUBLIC_DSN___', {
  release: '1.3.0'
  - }).install()
  + }).install();
  Those configuration options are documented below:
  