Note when Type is not an expected type for any properties

[RichardWallis]

Transferred from schemaorg issue (#2286) as problem is in code now in this repo.

Comment from @jvandriel in original issue:

Thanks for checking @RichardWallis !

I was looking for Patient code examples when I noticed there weren't any properties mentioned that expect it as their value. Just wanted to make sure I hadn't uncovered a bug.

Though might I request that somewhere in the future pages show a message stating:

"Instances of $type are not expected as values for any properties at the moment"

as opposed to simply omitting the entire area below:

"Instances of $type may appear as values for the following properties"

Having such a 'non-voluminous' message would have helped greatly already because I would have known not to look any further.

Comment from @RichardWallis
Perhaps:

"Instances of $type are not expected as values for any properties at the moment, however they may be used as values for properties that expect one of its super-types"