Deprecate LS Netflow module and point to FB Netflow module

Fixes #11113

docs/static/modules.asciidoc

@@ -8,7 +8,7 @@ These modules are available:
 
 * <<connecting-to-cloud,Elastic Cloud>>
 * <<arcsight-module>>
-* <<netflow-module>>
+* <<netflow-module,Netflow Module (deprecated)>>
 * <<azure-module, Microsoft Azure Module>>
 
 Each module comes pre-packaged with Logstash configurations, Kibana dashboards,

docs/static/netflow-module.asciidoc

@@ -2,9 +2,11 @@
 === Logstash Netflow Module
 
 ++++
-<titleabbrev>Netflow Module</titleabbrev>
+<titleabbrev>Netflow Module (deprecated)</titleabbrev>
 ++++
 
+deprecated[7.4.0, Replaced by the {filebeat-ref}/filebeat-module-netflow.html[{Filebeat} Netflow Module] which is compliant with the {ecs-ref}/index.html[Elastic Common Schema (ECS)]]
+
 The Logstash Netflow module simplifies the collection, normalization, and
 visualization of network flow data. With a single command, the module parses
 network flow data, indexes the events into Elasticsearch, and installs a suite
@@ -12,6 +14,7 @@ of Kibana dashboards to get you exploring your data immediately.
 
 Logstash modules support Netflow Version 5 and 9.
 
+
 ==== What is Flow Data?
 
 Netflow is a type of data record streamed from capable network devices. It
@@ -34,6 +37,10 @@ install.
 [[netflow-getting-started]]
 ==== Getting Started
 
+NOTE: The {ls} Netflow Module has been deprecated and replaced by the
+{filebeat-ref}/filebeat-module-netflow.html[{Filebeat} Netflow Module], which is
+compliant with the {ecs-ref}/index.html[Elastic Common Schema (ECS)].
+
 . Start the Logstash Netflow module by running the following command in the
 Logstash installation directory:
 +