Enable speech to text

We have Jigasi up and running and could easily add speech-to-text with Vosk. Install the german model:

  docker run -d -p 2700:2700 alphacep/kaldi-de:latest

add to /etc/jitsi/jigasi/sip-communicator.properties

  org.jitsi.jigasi.transcription.customService=org.jitsi.jigasi.transcription.VoskTranscriptionService

See https://github.com/jitsi/jigasi#vosk-configuration