Rollup merge of #35281 - apasel422:repr, r=GuillaumeGomez
Rollup merge of #35281 - apasel422:repr, r=GuillaumeGomez

Clean up `std::raw` docs

There is no longer a `Repr` trait, so mentioning a missing impl of it was potentially confusing.

r? @steveklabnik

graydon/rust,graydon/rust,GBGamer/rust,aidancully/rust,aidancully/rust,aidancully/rust,GBGamer/rust,aidancully/rust,graydon/rust,GBGamer/rust,GBGamer/rust,GBGamer/rust,graydon/rust,aidancully/rust,GBGamer/rust,GBGamer/rust,graydon/rust,aidancully/rust,GBGamer/rust,graydon/rust