[version.syn] Added freestanding for type_order

[hewillk]

Although <compare> already shows // all freestanding, it still seems useful to add freestanding here, which is consistent with __cpp_lib_three_way_comparison, which is annotated with // freestanding, also in <compare>.

Or is this LWG?

[eisenwave]

Traditionally, changes to the // freestanding comments in [version.syn] have been done via LWG issue, such as LWG4126, but maybe @jwakely would be open to processing this one editorially.