chore: fix doc test

Signed-off-by: MrCroxx <[email protected]>

src/lib.rs

@@ -21,6 +21,7 @@
 //! It also provides its human readable string as follows:
 //!
 //! ```
+//! # use foyer_bytesize as bytesize;
 //! use bytesize::ByteSize;
 //!
 //! assert_eq!("482.4 GiB", ByteSize::gb(518).to_string_as(true));