Mount bigbluebutton-release in bbb_exporter

This is needed for bbb_exporter to export the deployed BBB version.

templates/monitoring/docker-compose.yaml.j2

@@ -5,6 +5,7 @@ services:
     image: greenstatic/bigbluebutton-exporter:{{ bbb_monitoring_exporter_version }}
     network_mode: host
     volumes:
+      - "/etc/bigbluebutton/bigbluebutton-release:/etc/bigbluebutton/bigbluebutton-release:ro"
       # Can be removed if `RECORDINGS_METRICS_READ_FROM_DISK` is set to false (or omitted).
       # See https://bigbluebutton-exporter.greenstatic.dev/exporter-user-guide/#optimizations for details.
       - "/var/bigbluebutton:/var/bigbluebutton:ro"