Merge pull request #432 from RalfJung/rfc-2645

add incompleteness notes

Author: RalfJung

reference/src/layout/enums.md

@@ -7,6 +7,9 @@ and which parts are still in a "preliminary" state, at least until we
 start to open RFCs ratifying parts of the Unsafe Code Guidelines
 effort.
 
+**Note:** This document has not yet been updated to
+[RFC 2645](https://github.com/rust-lang/rfcs/blob/master/text/2645-transparent-unions.md).
+
 [#10]: https://github.com/rust-rfcs/unsafe-code-guidelines/issues/10
 
 ## Categories of enums

reference/src/layout/unions.md

@@ -4,6 +4,9 @@
 [#13].  The statements in here are not (yet) "guaranteed"
 not to change until an RFC ratifies them.
 
+**Note:** This document has not yet been updated to
+[RFC 2645](https://github.com/rust-lang/rfcs/blob/master/text/2645-transparent-unions.md).
+
 [#13]: https://github.com/rust-rfcs/unsafe-code-guidelines/issues/13
 
 ### Layout of individual union fields