Add a link to the maintained code base to README

[ghost]

According to #1 (comment) this repository is no longer maintained, and the new code base can be found here - https://github.com/KinesisCorporation/SmartSetApps

Please add a README to this repo , indicate that this repo is no longer maintained, and link to the maintained code base. Possibly archive the repository if no work is planned in the foreseeable future.

Additionally, this page https://kinesis-ergo.com/support/advantage2/#smartset-app still links to this code base. It might be useful to also update the link there as well.

Thank you!