Constraints example notebook typos fix (#449)

* Fix typos and add example for the missing values proportion constraint in Constraints_Suite

Co-authored-by: pecop2 <petar@loka.com>
Co-authored-by: MilenaTrajanoska <trajanoska28@gmail.com>
Co-authored-by: Jamie Broomall <88007022+jamie256@users.noreply.github.com>