chore: add deprecation warning to redis-4

Author: blumamir

plugins/node/opentelemetry-instrumentation-redis-4/README.md

@@ -1,5 +1,7 @@
 # OpenTelemetry redis Instrumentation for Node.js
 
+> ⚠️ **DEPRECATED**: The support for `redis@4` instrumentation is now part of `@opentelemetry/instrumentation-redis`. please use it instead.
+
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