Auto merge of #30088 - sourcefrog:doc-casts, r=steveklabnik
Auto merge of #30088 - sourcefrog:doc-casts, r=steveklabnik

Based on the description in https://github.com/rust-lang/rust/blob/219eca11b044de3644b3e9101124513c1a842b09/src/librustc_typeck/check/cast.rs#L11 and https://doc.rust-lang.org/nightly/nomicon/casts.html

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