mod-dnstap: sink (file) is opened for truncate: should be documented

knot-2.5.4 with the following config:

mod-dnstap:
  - id: knot-2.5.4
    sink: /root/taps/knot-auth.tap

The file I reference for sink is opened for truncate: I believe this ought to be documented (possibly with a warning?) or rather changed to have the file opened for append. To be honest I was a little surprised that the file was truncated.

Related question: when knot is running, is there actually a signal I can send to it to have knot reopen the file? I'm thinking in terms of rotation.