Export PhysAddrNotValid and VirtAddrNotValid (#163)

Those two structs are exported by making the `addr` module public.

Author: samueltardieu

src/addr.rs

@@ -1,3 +1,5 @@
+//! Physical and virtal addresses manipulation
+
 use core::fmt;
 use core::ops::{Add, AddAssign, Sub, SubAssign};
 

src/lib.rs

@@ -35,12 +35,11 @@ macro_rules! const_fn {
 #[cfg(not(feature = "inline_asm"))]
 pub(crate) mod asm;
 
+pub mod addr;
 pub mod instructions;
 pub mod registers;
 pub mod structures;
 
-mod addr;
-
 /// Represents a protection ring level.
 #[derive(Debug, Copy, Clone, PartialEq, Eq)]
 #[repr(u8)]