Add exports header to module docs

crates/lb/src/fs.rs

@@ -1,5 +1,7 @@
 //! The `lb:fs` module provides utilities for interacting with the file system asynchronously.
 //!
+//! # Exports
+//!
 //! See [`lb_libfs`] for items exported by this module.
 use luaffi::{cdef, metatype};
 use std::io;