message: doc(deprecated) Improve `README.md`s.
diff: # Wasmer deprecated packages
  -We create "wrapping" crates to ease the adodption of new
  -versions of Wasmer, with minimal or no breaking changes.
  +## Important Note; Please Read
  +Thanks to users' feedbacks, collected experience and various usecases,
  +Wasmer has decided to entirely changed its API to offer the best user
  +experience and the best features to as many users as possible, just
  +before the 1.0 release. This new version of Wasmer includes many
  +improvements in terms of performance or the memory consumption, in
  +addition to a ton of new features and much better flexibility!
  +
  +In order to help our existing users to enjoy the performance boost and
  +memory improvements without updating their program that much, we have
  +created a new version of the `wasmer-runtime-core` crate, which is now
  +*a port* of the new API but with the old API, as much as
  +possible. Indeed, it was not always possible to provide the exact same
  +API, but changes are subtle.
  +
  +We have carefully documented most of the differences in [the
  +`runtime-core/CHANGES.md` document](./runtime-core/CHANGES.md).
  +
  +It is important to understand the public of this port. We do not
  +recommend to advanced users of Wasmer to use this port. Advanced API,
  +like `ModuleInfo` or the `vm` module (incl. `vm::Ctx`) have not been
  +fully ported because it was very internals to Wasmer. For advanced
  +users, we highly recommend to migrate to the new version of Wasmer,
  +which is awesome by the way (completely neutral opinion). The public
  +for this port is beginners or regular users that do not necesarily
  +have time to update their code immediately but that want to enjoy a
  +performance boost and memory improvements.
  