OSDOCS-6796: Adding final deprecation notice for 1.0 channel

Author: skrthomas

networking/network_observability/network-observability-operator-release-notes.adoc

@@ -19,6 +19,10 @@ The following advisory is available for the Network Observability Operator 1.3.0
 
 * link:https://access.redhat.com/errata/RHSA-2023:3905[RHSA-2023:3905 Network Observability Operator 1.3.0]
 
+[id="network-observability-channel-deprecation"]
+=== Channel deprecation
+You must switch your channel from `v1.0.x` to `stable` to receive future Operator updates. The `v1.0.x` channel is deprecated and planned for removal in the next release.
+
 [id="network-observability-operator-1.3.0-features-enhancements"]
 === New features and enhancements