add a few docker containers definitions and compiled a list of what is still missing

DOCKER.md

akka-bbb-apps/Dockerfile

akka-bbb-fsesl/Dockerfile

akka-bbb-transcode/Dockerfile

...in/scala/org/bigbluebutton/api2/SystemConfiguration.scala

bbb-webhooks/Dockerfile

bigbluebutton-web/Dockerfile

freeswitch.dockerfile

labs/bbb-webrtc-sfu/Dockerfile

labs/bbb-webrtc-sfu/bbb-webrtc-sfu-run.sh

libreoffice-run.sh

libreoffice.dockerfile

sbt.dockerfile