Rollup merge of #34976 - GuillaumeGomez:build_hasher_doc, r=steveklabnik
Rollup merge of #34976 - GuillaumeGomez:build_hasher_doc, r=steveklabnik

Add BuildHasher example

r? @steveklabnik

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