update docs

src/lib.rs

@@ -3,7 +3,7 @@
 //! ```
 //! # #![feature(generic_const_exprs)]
 //! use diman::si::dimensions::{Length, Time, Velocity};
-//! use diman::si::units::{seconds, meters, kilometers, hours};
+//! use diman::si::units::{seconds, meters, kilometers, hours, hour};
 //!
 //! fn get_velocity(x: Length<f64>, t: Time<f64>) -> Velocity<f64> {
 //!     x / t
@@ -13,9 +13,10 @@
 //! let v2 = get_velocity(10.0 * meters, 1.0 * seconds);
 //!
 //! assert_eq!(v1, v2);
+//! assert_eq!(format!("{} km/h", v1.value_in(kilometers / hour)), "36 km/h");
 //! ```
 //!
-//! Let's try to add quantities with incompatible dimensions:
+//! Diman prevents unit errors at compile time:
 //! ```compile_fail
 //! # use diman::si::units::{seconds, meters};
 //! let time = 1.0 * seconds;