message: docs: Mention metadata predicate change
diff: @@ -26,6 +26,7 @@ These changes are relevant if you wrote custom modules for the server that depen
  - The `ResourceStore` function `resourceExists` has been renamed to `hasResource`
  and has been moved to a separate `ResourceSet` interface.
  - Several `ModesExtractor`s `PermissionBasedAuthorizer` now take a `ResourceSet` as constructor parameter.
  +- `RepresentationMetadata` no longer accepts strings for predicates in any of its functions.
  ## v3.0.0
  ### New features
  