Rollup merge of #59390 - czipperz:ptr_eq_smart_pointer, r=Centril,steveklabnik
Rollup merge of #59390 - czipperz:ptr_eq_smart_pointer, r=Centril,steveklabnik

Make `ptr::eq` documentation mention fat-pointer behavior

Resolves #59214

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