Guideline 5c+ does not belong to a regulation

[coder13]

[lgarron]

As mentioned in #1179 (comment) , this is not an issue in itself. There is no need for a Guideline number to match up to a Reg. In this case, the Guideline used to be Regulation 5c) and has been moved to 5c++).

I think it would be less disruptive to keep it as-is, although there isn't anything stopping us from renumbering it (e.g. to 5b++) either.