Update readme

README.rst

@@ -3,6 +3,8 @@ Kitsune
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+**This branch is locked and does not accept any commits. The code here powered support.mozilla.org while on SCL3 datacenter. Since March 2018 SUMO has been moved to kubernetes/AWS and development happens in `master` branch.**
+
 Kitsune is the platform that powers `SuMo (support.mozilla.org)
 <https://support.mozilla.org>`_