docs: Update readme for deprecation (#6)

README.rst

@@ -1,6 +1,17 @@
 event-bus-redis plugin for `Tutor <https://docs.tutor.overhang.io>`__
 ===================================================================================
 
+DEPRECATED AND ARCHIVED
+-----------------------
+
+This repository never went into use because it was overkill for just
+managing a few settings. It is just an empty cookiecutter template.
+
+There may be useful context for setting up a new plugin that handles
+event bus configuration and consumer running for both redis and Kafka in the
+bmtcril/add_kafka branch.
+
+
 Installation
 ------------
 
@@ -19,4 +30,4 @@ Usage
 License
 -------
 
-This software is licensed under the terms of the AGPLv3.
+This software is licensed under the terms of the AGPLv3.