Placeholder #repr_ty_name in derived attribute wrapper type documentation

[kpreid]

The wrapper types generated by #[derive(Semantics)] have documentation text that is literally

Vertex attribute type (representing #repr_ty_name).

instead of substituting the type name as was presumably intended. Using luminance-derive version 0.8.0.

[hadronized]

Argh yeah… I’m not even sure it’s possible to substitute it :(

[kpreid]

Use the #[doc] syntax for doc comments (/// is sugar):

let doc_string = format!("Vertex attribute type (representing {}).", repr_ty_name);
quote! {
    #[doc = #doc_string]
    fn ...
}