(core): index of activities
Description
New becomers complain about the lack of clean index of services in the first place, but this is also hard to know which activity can be included in your application.
Proposal
We should provide a nice index of activities, at least the most used in a first time. They should be sorted by category. Doing this manually could be tedious. Since we follow a strict xsd to describe them, it is probably possible to generate this. Either with xslt, or with a python script, or even maybe it is possible to use Sphinx to this end.