doc(vignettes): updates following the optional Qobs in CreateInputsModel

Refs #60
2 jobs for 60-createinputsmodel-make-qobs-parameter-optional in 5 minutes and 50 seconds (queued for 12 seconds)
Status Name Job ID Coverage
  Checks
passed check_as_cran #211477
docker

00:05:49

passed check_not_cran #211476
docker

00:05:07