Add vignette for combined vacccination and intervention scenarios

[pratikunterwegs]

Maybe including an example of this combination? even if it is just example code, also for users to visualise how to make the list with vaccination and interventions and specifying when there is no intervention/vaccination for the different scenarios
Otherwise it's a bit dry to read without anything to put into practice

Originally posted by @CarmenTamayo in #176 (comment)

[pratikunterwegs]

Moving this to the Discussion tab as the interventions and vaccination functionalities are already shown in separate vignettes.