fix: update Agent 2.x banner (#797)

Updates NGINX Agent 2.x docs banner to clarify the scope of the docs.

Author: JTorreG

_banners/agent-v3-release.md

@@ -1,7 +1,8 @@
 {{< banner "notice" "NGINX Agent 3.0 is now available" >}}
 
+The documentation in this section is for **NGINX Agent version 2.x**. For NGINX Agent 3.x content visit the [NGINX One Console documentation]({{< ref "/nginx-one/agent/" >}})
 
-F5 NGINX Instance Manager (NIM) does not currently support Agent 3.x. NGINX Instance Manager customers can upgrade to the latest Agent 2.x version by following the [Upgrade NGINX Agent](/nginx-agent/installation-upgrade/upgrade/) guide.
+F5 NGINX Instance Manager (NIM) does not currently support NGINX Agent 3.x. NGINX Instance Manager customers can upgrade to the latest NGINX Agent 2.x version by following the [Upgrade NGINX Agent](/nginx-agent/installation-upgrade/upgrade/) guide.
 
 Please see the [Technical specifications](/nginx-agent/technical-specifications/) for product compatibility.