No clear documentation in terms of information being collected by default which includes PII

[yangsu-ab]

Recently we noticed the Airbrake library was trying to access our rail user model's data. specifically we traced the call to
https://github.com/airbrake/airbrake/blob/master/lib/airbrake/rack/user_filter.rb which was triggered from performance statistics.

This makes us believe that airbrake is collecting our PII information by default. We cannot find clear documentation in terms of how to completely disable this feature/functionality from the readme.

Few questions which might be useful to answer in the official readme:

1. what information is airbrake collecting by default?
2. is user information being collected only as part of performance statistics, or is it collected always, even for bug reporting.
3. how can we disable all/specific predefined filters.
4. are all the filters applied to both performance statistics and regular bug reports?