Update library/core/src/ptr/mod.rs

Co-authored-by: Ralf Jung <[email protected]>

Author: joshlf

library/core/src/ptr/mod.rs

@@ -66,6 +66,10 @@
 //! a separate allocated object), and `static` variables.
 //!
 //! It is guaranteed that an allocated object never spans more than `isize::MAX` bytes.
+//! An allocated object can never contain the null address, and the address "at the end"
+//! (i.e., one past the last byte that is contained inside the allocated object) can always
+//! be computed without wrapping around the address space. (The last part is equivalent
+//! to saying that `usize::MAX` is never contained in an allocated object.)
 //!
 //! # Strict Provenance
 //!