Update library/core/src/alloc/layout.rs

Co-authored-by: David Tolnay <dtolnay@gmail.com>

Author: joshlf

library/core/src/alloc/layout.rs

@@ -131,7 +131,7 @@ impl Layout {
 
     /// The minimum byte alignment for a memory block of this layout.
     ///
-    /// The returned alignment is guaranteed to be a non-zero power of two.
+    /// The returned alignment is guaranteed to be a power of two.
     #[stable(feature = "alloc_layout", since = "1.28.0")]
     #[rustc_const_stable(feature = "const_alloc_layout_size_align", since = "1.50.0")]
     #[must_use = "this returns the minimum alignment, \