Document `notify::event::EventAttributes::info`

[bicarlsen]

It doesn't appear there is any documentation about what information notify::event::EventAttributes::info represents. e.g. What values are possible here? If info is Some("override"), what does this mean?

It seems there are only a few places info is set:

1. https://github.com/notify-rs/notify/blob/128bf6230c03d39dbb7f301ff7b20e594e34c3a2/notify/src/fsevent.rs#L114
2. https://github.com/notify-rs/notify/blob/128bf6230c03d39dbb7f301ff7b20e594e34c3a2/notify/src/fsevent.rs#L159
3. https://github.com/notify-rs/notify/blob/128bf6230c03d39dbb7f301ff7b20e594e34c3a2/notify-debouncer-full/src/lib.rs#L469