Since rspamd 1.9.2 we'll be able to load custom modules from plugins.d
directory.
This allow to add and configure plugins easily from the
data/conf/rspamd/plugins.d
Also loading config for custom plugins need rspamd.conf.local or
optionally rspamd.conf.override.
I added support for this in the docker-compose.yml
Idea came while i was writing a custom plugin for Cyren antispam
gateway, which can be found here: https://github.com/sriccio/rspamd-plugins