help facilities

[mvolkmann]

I understand that Scryer has not been in development for as long as some other Prolog implementations and that's a very valid reason for some features to be missing.

Does Scryer currently implement any predicates that provide help? For example, in SWI-Prolog I can use the apropos, help, and listing predicates for various kinds of help. And after entering a query I can press ? to get help on supported keys. Maybe something similar to these is available in Scryer, but I just haven’t found them yet.

[pmoura]

Related: #1615