Update references.rs (#24)

an -> a

src/references.rs

@@ -1,11 +1,11 @@
 //! Reimplementations of [`std::ptr::null()`] and [`std::ptr::null_mut()`], with safe code only.
 //! Relies on [`crate::transmute`] under the hood.
 
-/// Equivalent to [`std::ptr::null()`], but returns an null reference instead.
+/// Equivalent to [`std::ptr::null()`], but returns a null reference instead.
 pub fn null<'a, T: 'static>() -> &'a T {
 	crate::transmute(0usize)
 }
-/// Equivalent to [`std::ptr::null_mut()`], but returns an mutable null reference instead.
+/// Equivalent to [`std::ptr::null_mut()`], but returns a mutable null reference instead.
 pub fn null_mut<'a, T: 'static>() -> &'a mut T {
 	crate::transmute(0usize)
 }