Update the API files.
- lib/dns:
  - struct resolver has added elements, this is an interface change
    and thus LIBINTERFACE is incremented, and LIBREVISION is reset.
  - Since this also means an interface change since the last public
    release, also reset LIBAGE.
- lib/isc:
  - The library source code changed, so increment LIBREVISION.
- lib/isccfg:
  - The library source code changed, so increment LIBREVISION.

Update other files:
- No changes needed to the README, this is a small bugfix release.
- Fix a bad version xml:id in the release notes.