Update primitive_docs.rs

Author: joshlf

library/core/src/primitive_docs.rs

@@ -1399,9 +1399,8 @@ mod prim_usize {}
 /// * `t` is aligned to `align_of_val(t)`
 /// * `t` is dereferenceable for `size_of_val(t)` many bytes
 ///
-///  Being "dereferenceable" for N bytes means that the memory range beginning
-/// at the address `t` points to and ending N bytes later is all contained within a
-/// single [allocated object].
+/// If `t` points at address `a`, being "dereferenceable" for N bytes means that the memory range
+/// `[a, a + N)` is all contained within a single [allocated object].
 ///
 /// [allocated object]: ptr#allocated-object
 #[stable(feature = "rust1", since = "1.0.0")]