Rollup merge of #34855 - GuillaumeGomez:vec_deque_doc, r=steveklabnik
Rollup merge of #34855 - GuillaumeGomez:vec_deque_doc, r=steveklabnik

Add examples for VecDeque

Part of #29348.

r? @steveklabnik

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