Rollup merge of #74548 - tshepang:one-more-example, r=dtolnay
Rollup merge of #74548 - tshepang:one-more-example, r=dtolnay

one more Path::with_extension example, to demonstrate behavior

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