Add deprecation notice

README.md

@@ -1,2 +1,11 @@
 # mig-selfservice
 MIG self service portal
+
+⚠️ Deprecation Notice ⚠️
+-------------------------
+
+Mozilla is no longer maintaining the Mozilla InvestiGator (MIG) project.
+
+Mozilla is also no longer making use of this code internally.
+
+You are welcome to use this code as is with no warranty. Please fork it to continue development.