Update Decidim documentation about Participatory Spaces

[Dynnammo]

If I take a look here, https://docs.decidim.org/en/features/participatory-spaces/, I see there's only 4 different types of participatory spaces described, but if I'm mistaking, we added consultations and votations since.

Am I mistaking ?

If not, I think we should document such spaces.

[paulinebessoles]

@Dynnammo Consultations and votations have been deprecated, but we should definitely add Conferences there!