Add a hint to the Supported Features table to show if additional constraints apply

[nigelmegitt]

The Supported Features table in §6 Supported Features simply lists the disposition for each feature, but does not provide a hint that there may be an additional constraint in §7.12 Constraints.

I suggest appending to "permitted" or "optional" dispositions the text ", constrained" where the word "constrained" is a link to the relevant constraint section.