Macro tool_doc

macro_rules! tool_doc {
    (
        $tool: ident,
        $path: literal,
        $(rustc_tool = $rustc_tool:literal, )?
        $(is_library = $is_library:expr,)?
        $(crates = $crates:expr)?
        $(, submodule $(= $submodule:literal)? )?
       ) => { ... };
}