Document that `QuantifiedConstraints` implies `ExplicitForAll`
Summary
The GHC user's guide doesn't state that QuantifiedConstraints
implies ExplicitForAll
, which it does as can be seen.
I took the trouble to verify the rest of the extension implications in the linked source. The good news is that this is the only remaining undocumented relationship. May no new ones be introduced.
Proposed improvements or changes
Document the implication.