Additional example for @deprecated

[OlMue]

As discussed with @margopolo and the UA colleagues: In case of deprecations, either the user needs information about whether there is an alternative to the deprecated element, or it needs to be indicated that the concept has been discarded. This PR adds an additional example for the latter. I also removed the part about "internal releases" since this isn't really a common thing anymore and thus doesn't need to be part of these guidelines.

[margopolo]

The correct reference is that the user needs information about whether there is an alternative to the deprecated element, or it needs to be indicated that the API was deprecated without replacement (e.g. because the concept has been discarded).