Clumsy language in "Follow-set Ambiguity Restrictions" of Macros by example

[tialaramex]

As it stands the text reads:

In particular, in addition to the rule about ambiguous expansions, a nonterminal matched by a metavariable must be followed by a token which has been decided can be safely used after that kind of match.

"which has been decided can be safely used" sounds awkward to me, the general meaning is apparent, but there must be a nicer option so I think it should be improved and this Issue is about how to do that.

Maybe we can introduce some agency. "which the Rust Language Team has decided can be safely used"? (but we should make sure that if a specific person or group is named, that's the right one)

Or maybe deliberately don't, "which it has been decided can be safely used"? Leaving it to an interested reader to investigate how this was decided and what processes control this decision.