Rollup merge of #42195 - SamWhited:fix_broken_link, r=steveklabnik
Rollup merge of #42195 - SamWhited:fix_broken_link, r=steveklabnik

fix broken link to nomicon in Unsize docs

Add a missing link that is currently broken in the docs (see the last sentence of https://doc.rust-lang.org/std/marker/trait.Unsize.html)

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