(core): add an example of how to create an activity.
Add an example of how to create or use an activity. Currently there is only a basic description of the XML description of an activity.
Explain how to create and use an activity in a complete application.
- create the activity in XML
- how to connect the services in the XML (SDynamicView, SActivityWizard, SCreateActivity, ...)
Links / references
Existing documentation for Activities: https://fw4spl.readthedocs.io/en/dev/SAD/src/SDM-SAD-Activities.html