Rollup merge of #49105 - SimonSapin:from_utf8_lossy_example, r=alexcrichton
Rollup merge of #49105 - SimonSapin:from_utf8_lossy_example, r=alexcrichton

Add an example of lossy decoding to str::Utf8Error docs

CC https://github.com/rust-lang/rust/issues/33906

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