Question.available() should show the question type class name

[rbyh]

Current output is less helpful because user needs to know the name to import:

Consider also returning a message reminder (below the list of types) that the .example() method will show an example of a type in the required template, e.g., QuestionMultipleChoice.example()

[rbyh]

I do think we should leave this list in alphabetical order, even though docs details are organized by importance of question type (MC first).