Rollup merge of #40226 - jdhorwitz:master, r=frewsxcv
Rollup merge of #40226 - jdhorwitz:master, r=frewsxcv

Issue #39688 - Help people find String::as_bytes() for UTF-8

Added in links for the inverse functions so people will know that as_bytes() is the inverse of from_utf8() and vice versa.
?r @steveklabnik

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