docs: Add usage guide on Kubernetes executors (#373)

docs/modules/airflow/pages/usage-guide/logging.adoc

@@ -17,7 +17,7 @@ spec:
             loggers:
               "flask_appbuilder":
                 level: WARN
-  workers:
+  celeryExecutors:
     config:
       logging:
         enableVectorAgent: true

docs/modules/airflow/pages/usage-guide/storage-resources.adoc

@@ -21,7 +21,7 @@ spec:
           max: "2"
         memory:
           limit: 512Mi
-  workers:
+  celeryExecutors:
     config:
       resources:
         cpu:

docs/modules/airflow/pages/usage-guide/using-kubernetes-executors.adoc

@@ -0,0 +1,29 @@
+= Using Kubernetes executors
+
+Instead of using the Celery workers you can let Airflow run the tasks using Kubernetes executors, where pods are created dynamically as needed without jobs being routed through a redis queue to the workers.
+
+To achieve this, swap `spec.celeryExecutors` with `spec.kubernetesExecutors`.
+E.g. you would change the following example
+
+[source,yaml]
+----
+spec:
+  celeryExecutors:
+    roleGroups:
+      default:
+        replicas: 2
+    config:
+      resources:
+        # ...
+----
+
+to
+
+[source,yaml]
+----
+spec:
+  kubernetesExecutors:
+    config:
+      resources:
+        # ...
+----

docs/modules/airflow/partials/nav.adoc

@@ -10,6 +10,7 @@
 ** xref:airflow:usage-guide/security.adoc[]
 ** xref:airflow:usage-guide/logging.adoc[]
 ** xref:airflow:usage-guide/monitoring.adoc[]
+** xref:airflow:usage-guide/using-kubernetes-executors.adoc[]
 ** xref:airflow:usage-guide/overrides.adoc[]
 ** xref:airflow:usage-guide/operations/index.adoc[]
 *** xref:airflow:usage-guide/operations/cluster-operations.adoc[]