explain what's wrong about the provenance

Author: RalfJung

reference/src/glossary.md

@@ -78,7 +78,9 @@ let raw2_wrong = raw1.wrapping_add(raw2.wrapping_sub(raw1 as usize) as usize);
 // In other words, raw2 and raw2_wrong have same *address*...
 assert_eq!(raw2 as usize, raw2_wrong as usize);
 // ...but it would be UB to use raw2_wrong, as it was obtained by
-// cross-allocation arithmetic. raw2_wrong has the wrong *provenance*.
+// cross-allocation arithmetic. raw2_wrong has the wrong *provenance*:
+// it points to address 0x200 in allocation @2, but the pointer
+// has provenance @1.
 ```
 
 Another example of pointer provenance is the "tag" from [Stacked Borrows][stacked-borrows].