docs: Add page descriptions

docs/modules/listener-operator/pages/installation.adoc

@@ -1,4 +1,5 @@
 = Installation
+:description: Installation of the Stackable listener operator with stackablectl or Helm, covering ListenerClass presets and settings for Kubernetes distributions.
 
 There are two ways to run the Stackable Listener Operator:
 

docs/modules/listener-operator/pages/overview.adoc

@@ -1,4 +1,5 @@
 = Overview
+:description: Overview of the Stackable listener operator, covering why exposing services in Kubernetes is hard and how it handles access scope, routing and addresses.
 
 So. You've deployed something, and now you want let people call into it.
 Just grab the IP address, port, maybe punch a hole through the firewall if you're feeling particularly adventurous, and you're off to the races... right?

docs/modules/listener-operator/pages/reference/commandline-parameters.adoc

@@ -1,4 +1,5 @@
 = Command line parameters
+:description: Command-line parameters the Stackable listener operator accepts, such as the required CSI endpoint socket path, with their environment variable equivalents.
 
 This operator accepts the following command line parameters:
 

docs/modules/listener-operator/pages/reference/crds.adoc

@@ -1,3 +1,4 @@
 = CRD Reference
+:description: CRD reference for the Stackable listener operator on the Stackable Hub, covering every field, default and API version.
 
 Find all CRD reference for the Stackable Listener Operator at: {crd-ref}{crd-ref-release}&operator=listener-operator.

docs/modules/listener-operator/pages/reference/environment-variables.adoc

@@ -1,4 +1,5 @@
 = Environment variables
+:description: Environment variables the Stackable listener operator accepts, including the required CSI endpoint socket, with what each one controls and its default.
 
 This operator accepts the following environment variables:
 

docs/modules/listener-operator/pages/reference/index.adoc

@@ -1,4 +1,5 @@
 = Reference
+:description: Reference for the Stackable listener operator, covering CRD fields, command-line parameters and environment variables, with their default values.
 
 Consult the reference documentation section to find exhaustive information on:
 

docs/modules/listener-operator/pages/usage.adoc

@@ -1,4 +1,5 @@
 = Usage
+:description: Usage of the Stackable listener operator, covering listenerClass settings in SDP operators, the exposed addresses and use in other applications.
 
 The Listener Operator is used differently depending on whether you are using Stackable data platform operators or building custom applications.