OSDOCS-400: Stating the supported OSDK version

Author: bergerhoffer

applications/operator_sdk/osdk-getting-started.adoc

@@ -14,6 +14,8 @@ This is accomplished using two centerpieces of the Operator Framework: the
 Operator SDK (the `operator-sdk` CLI tool and `controller-runtime` library API)
 and the Operator Lifecycle Manager (OLM).
 
+NOTE: {product-title} 4 supports Operator SDK 0.7.0 or later.
+
 include::modules/osdk-architecture.adoc[leveloffset=+1]
 include::modules/osdk-monitoring-prometheus-operator-support.adoc[leveloffset=+2]