Fix incorrect documentation for `unstable_features`
Fix incorrect documentation for `unstable_features`
SingingTree/rustfmt,aidancully/rust,aidancully/rust,graydon/rust,graydon/rust,graydon/rust,aidancully/rust,graydon/rust,aidancully/rust,graydon/rust,rust-lang/rustfmt,rust-lang/rustfmt,graydon/rust,aidancully/rust,SingingTree/rustfmt,aidancully/rust