[optional.inplace] "argument pack" should be "function parameter pack"

[sdutoit]

Alisdair says:

[optional.inplace] 20.6.5 In-place construction
p1
The standard does not define a term 'argument pack', the correct
term is 'function parameter pack'.

[jwakely]

Yes, I mentioned this in c++std-lib-34059

I discussed it with Andrzej Krzemienski and I suggested this rewording:

Specifically, optional<T> has a constructor with in_place_t as the
first argument followed by a function parameter pack; this indicates
that T should be constructed in-place (as if by a call to placement
new expression) with the pack expansion forming the constructor
arguments.

He pointed out that "argument pack" is also used (without definition) in [temp.arg]/4

[sdutoit]

Closed by 0131a03. I in fact removed the sentence outright as it adds nothing to the existing normative wording for the constructors disambiguated by in_place_t.