Update lib.rs
typo
//!
//! ## Description
//!
-//! - `Reader`: a low leve xml pull-reader where buffer allocation/clearing is left to user
+//! - `Reader`: a low level xml pull-reader where buffer allocation/clearing is left to user
//! - `Writer`: a xml writer. Can be nested with readers if you want to transform xmls
//!
//! ## Examples
