Rollup merge of #77409 - pickfire:patch-6, r=GuillaumeGomez
Rollup merge of #77409 - pickfire:patch-6, r=GuillaumeGomez

Add example for iter chain struct

r? @GuillaumeGomez

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