another idea, could be to extend the additional field setting to another Docebo function like the course definition. This way we could for instance add a new field setting for Course Provider if you have in your compaby differente course providers.
before adding a new function, what you suggest may be already achieved with the course catalogue and the use of categories (one provider per category).
What do you think?
Anyway, if you intend this feature as a simple descriptive field it's quite simple, the hardest part would be define where tho show this information and how to use it.