Clarify doc text
//! Thread-local storage for JavaScript threads.
//!
//! At runtime, an instance of a Node.js addon can contain its own local storage,
-//! which can then be shared and accessed as needed between Rust modules. This can
+//! which can then be shared and accessed as needed from Rust in a Neon module. This can
//! be useful for setting up long-lived state that needs to be shared between calls
//! of an addon's APIs.
//!
