Apply suggestion from @rcseacord

Author: rcseacord

src/coding-guidelines/types-and-traits.rst

@@ -18,7 +18,7 @@ Types and Traits
    :release: 1.85.0
    :decidability: undecidable
    :scope: expression
-   :tags: unions, safety, undefined-behavior
+   :tags: defect, safety, undefined-behavior
 
    When reading from a union field, ensure that the underlying bytes constitute a valid value 
    for that field's type.