Addition of required / extensible / preferred / example terminology constraint to AOM and ADL

Specifications ADL
2

No opinion about what it should look like in ADL2, but I’d like to express a general HUZZAH! :partying_face:

This will make modelling much more flexible, and save us from the ugly DV_CODED_TEXT+DV_TEXT hack. Good work! :smiley: :+1:t2: