You will have to create the device nodes on the host before creating the docker, the documentation in the wiki is referring to Docker on a Synology NAS.
The nodes need to exist before you create and start a docker image because docker needs this to know which devices it should allow.
mkdir -p /dev/dvb/adapter0
mknod /dev/dvb/adapter0/frontend0 c 212 1
mknod /dev/dvb/adapter0/dvr0 c 212 5
mknod /dev/dvb/adapter0/demux0 c 212 3
mkdir -p /dev/dvb/adapter1
mknod /dev/dvb/adapter1/frontend0 c 212 7
mknod /dev/dvb/adapter1/dvr0 c 212 11
mknod /dev/dvb/adapter1/demux0 c 212 9
mkdir -p /dev/dvb/adapter2
mknod /dev/dvb/adapter2/frontend0 c 212 13
mknod /dev/dvb/adapter2/dvr0 c 212 17
mknod /dev/dvb/adapter2/demux0 c 212 15
so that was for the host, now in docker you have to install the driver like we've written in the wiki documentation.