Indicate that development has stopped on this repo

After talking with @mcclearyj, we have decided to merge the development of the meds-making code here into the `superbit-metacal` repo so it is all in one space. That means that this repo will soon be obsolete, so that should be indicated at the top of the readme.

Open the repository's README and review its current top section. Add a prominent notice that development has moved to the `superbit-metacal` repository and that this repository is becoming obsolete; done means the notice appears at the top and identifies the destination repository.

Written by the indexing model from the issue text.