codemap: Add module description
codemap: Add module description

graydon/rust,graydon/rust,studoot/rustfmt,Emilgardis/rustfmt,graydon/rust,graydon/rust,graydon/rust,aidancully/rust,rust-lang/rustfmt,aidancully/rust,rust-lang/rustfmt,studoot/rustfmt,graydon/rust,aidancully/rust,SingingTree/rustfmt,aidancully/rust,aidancully/rust,aidancully/rust,SingingTree/rustfmt,Emilgardis/rustfmt