Add docs on setting HA for Eventing

Lowercase "serverless-HA.adoc" and all references to it

Serving & Eventing: improve screenshots for changing replicas # in YAML

Add docs on setting HA for Kafka

Include the setting HA for Kafka module

Improve wording

Give more precise info, remove stale files, improve wording

Remove claim that HA can be disabled; improve style

Update the list of components scaled with HA

Add intros to modules, make info more precise, improve wording

Delete a rogue old assembly

Author: rh-max

images/eventing-YAML-HA.png

@@ -0,0 +1,53 @@
+// Module is included in the following assemblies:
+//
+// serverless/serverless-ha.adoc
+
+[id="serverless-config-replicas-eventing_{context}"]
+= Configuring high availability replicas for Eventing
+
+You can scale Knative Eventing components by modifying the `spec.high-availability.replicas` value in the KnativeEventing custom resource.
+
+.Prerequisites
+* You have access to an {product-title} cluster with cluster administrator permissions.
+* The {ServerlessOperatorName} and Knative Eventing are installed on your cluster.
+
+.Procedure
+
+. In the {product-title} web console *Administrator* perspective, navigate to *OperatorHub* -> *Installed Operators*.
++
+image::serving-installed-operator.png[Installed Operators page]
++
+. Select the `knative-eventing` namespace.
++
+. Click *Knative Eventing* in the list of *Provided APIs* for the {ServerlessOperatorName} to go to the *Knative Eventing* tab.
++
+image::eventing-tab-created.png[Knative Eventing tab]
++
+. Click *knative-eventing*, then go to the *YAML* tab in the *knative-eventing* page.
++
+image::eventing-YAML-HA.png[Knative Eventing YAML]
++
+. Modify the number of replicas in the `KnativeEventing` CRD:
++
+.Example YAML
+[source,yaml]
+----
+apiVersion: operator.knative.dev/v1alpha1
+kind: KnativeEventing
+metadata:
+  name: knative-eventing
+  namespace: knative-eventing
+spec:
+  high-availability:
+    replicas: 3 <1>
+----
+<1> Sets the number of replicas to `3`.
++
+[IMPORTANT]
+====
+Do not modify any YAML contained inside the `config` field. Some of the configuration values in this field are injected by the {ServerlessOperatorName}, and modifying them will cause your deployment to become unsupported.
+====
++
+* The `replicas` value sets the replica count for all HA controllers.
+* The default `replicas` value is `2`.
+* You can increase the number of replicas by changing the value to `3` or more.

images/eventing-tab-created.png

@@ -0,0 +1,49 @@
+[id="serverless-config-replicas-kafka_{context}"]
+= Configuring high availability replicas for Kafka
+
+You can scale Knative Kafka components by modifying the `spec.high-availability.replicas` value in the KnativeKafka custom resource.
+
+.Prerequisites
+* You have access to an {product-title} cluster with cluster administrator permissions.
+* The {ServerlessOperatorName} and Knative Kafka are installed on your cluster.
+
+.Procedure
+
+. In the {product-title} web console *Administrator* perspective, navigate to *OperatorHub* -> *Installed Operators*.
++
+image::kafka-installed-operator.png[Installed Operators page]
+
+. Select the `knative-eventing` namespace.
++
+. Click *Knative Kafka* in the list of *Provided APIs* for the {ServerlessOperatorName} to go to the *Knative Kafka* tab.
++
+image::kafka-tab-created.png[Knative Eventing tab]
++
+. Click *knative-kafka*, then go to the *YAML* tab in the *knative-kafka* page.
++
+image::kafka-YAML-HA.png[Knative Kafka YAML]
++
+. Modify the number of replicas in the `KnativeKafka` CRD:
++
+.Example YAML
+[source,yaml]
+----
+apiVersion: operator.serverless.openshift.io/v1alpha1
+kind: KnativeKafka
+metadata:
+  name: knative-kafka
+  namespace: knative-eventing
+spec:
+  high-availability:
+    replicas: 3 <1>
+----
+<1> Sets the number of replicas to `3`.
++
+[IMPORTANT]
+====
+Do not modify any YAML contained inside the `config` field. Some of the configuration values in this field are injected by the {ServerlessOperatorName}, and modifying them will cause your deployment to become unsupported.
+====
++
+* The `replicas` value sets the replica count for all HA controllers.
+* The default `replicas` value is `2`.
+* You can increase the number of replicas by changing the value to `3` or more.