take latest version of docker image from docker hub

[sebastiaan101]

use
docker pull odysseusinc/arachne-datanode-ce
or docker pull odysseusinc/arachne-datanode-ce:latest (?)
to get and install the right dockerversion

Now the wiki says odysseusinc/arachne-datanode-ce:1.16.2

[konstjar]

Update documentation with version placeholder