message: clarify caveats
diff: @@ -14,13 +14,13 @@ for example:
  * Not sufficiently aligned memory accesses and references
  * Violation of *some* basic type invariants (a `bool` that is not 0 or 1, for example,
  or an invalid enum discriminant)
  -* WIP: Violations of the rules governing aliasing for reference types
  +* **Experimental**: Violations of the rules governing aliasing for reference types
  Miri has already discovered some [real-world bugs](#bugs-found-by-miri). If you
  found a bug with Miri, we'd appreciate if you tell us and we'll add it to the
  list!
  -Be aware that Miri will not catch all cases of undefined behavior in your
  +Be aware that Miri will **not catch all cases of undefined behavior** in your
  program, and cannot run all programs:
  * There are still plenty of open questions around the basic invariants for some
  