fix const wording

[LiAuTraver]

per [N5008/decl.constexpr]:

The consteval specifier shall be applied only to the declaration of a function or function template.

and

The constexpr specifier shall be applied only to the definition of a variable or variable template, [...].

clause 6:

(object declared as constexpr) declares the object as const, shall have literal type and shall be initialized, and shall be constant-initializable.

[MaxXSoft]

Thank you for pointing this out! This version is indeed more accurate than the original text.

[MaxXSoft]

The CI failure was caused by temporary maintenance of https://gitlab.eduxiji.net/ , this can be ignored.

[MaxXSoft]

LGTM, Thank you!