Update comment about plugin registry.
Update comment about plugin registry.

mrpau/kolibri,mrpau/kolibri,learningequality/kolibri,indirectlylit/kolibri,indirectlylit/kolibri,mrpau/kolibri,indirectlylit/kolibri,learningequality/kolibri,learningequality/kolibri,indirectlylit/kolibri,mrpau/kolibri,learningequality/kolibri