Rollup merge of #44457 - napen123:master, r=frewsxcv
Rollup merge of #44457 - napen123:master, r=frewsxcv

Add doc examples for str::as_bytes_mut

Fixes #44427

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