Rollup merge of #40458 - frewsxcv:frewsxcv-osstr, r=GuillaumeGomez
Rollup merge of #40458 - frewsxcv:frewsxcv-osstr, r=GuillaumeGomez

Add doc examples for `OsStr`, `OsString`.

None

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