Build with docker (#163)

* Added example for building the documentation with a Docker utility container.

* Revert changes to local-antora-playbook.yml

* Fix README

Author: razvan

README.adoc

@@ -38,3 +38,12 @@ The design & layout comes from our https://github.com/stackabletech/documentatio
 
 A remote vscode instance can be used via https://gitpod.io/#/github.com/stackabletech/documentation
 
+=== Generate the documentation with a Docker utility container
+
+This method has the advantage that you don't need a local installation of Antora. The image `docker.stackable.tech/stackable/antora:3.0.1-stackable0` comes bundled with the required https://gitlab.com/antora/antora-lunr-extension[lunr] extension.
+
+[source,bash]
+----
+docker run -u $(id -u) -v $PWD:/antora:Z -w /antora --rm -t docker.stackable.tech/stackable/antora:3.0.1-stackable0 docker-antora-playbook.yml
+----
+

docker-antora-playbook.yml

@@ -0,0 +1,66 @@
+---
+site:
+  title: Stackable Documentation
+  url: https://docs.stackable.tech
+  start_page: home::index.adoc
+  robots: allow
+
+content:
+  sources: 
+    - url: ./
+      branches: HEAD
+
+    - url: https://github.com/stackabletech/secret-operator.git
+      branches: main
+      start_path: docs
+
+    - url: https://github.com/stackabletech/airflow-operator.git
+      branches: main
+      start_path: docs
+    - url: https://github.com/stackabletech/druid-operator.git
+      branches: main
+      start_path: docs
+    - url: https://github.com/stackabletech/hbase-operator.git
+      branches: main
+      start_path: docs
+    - url: https://github.com/stackabletech/hdfs-operator.git
+      branches: main
+      start_path: docs
+    - url: https://github.com/stackabletech/hive-operator.git
+      branches: main
+      start_path: docs
+    - url: https://github.com/stackabletech/kafka-operator.git
+      branches: main
+      start_path: docs
+    - url: https://github.com/stackabletech/nifi-operator.git
+      branches: main
+      start_path: docs
+    - url: https://github.com/stackabletech/opa-operator.git
+      branches: main
+      start_path: docs
+    - url: https://github.com/stackabletech/spark-operator.git
+      branches: main
+      start_path: docs
+    - url: https://github.com/stackabletech/superset-operator.git
+      branches: main
+      start_path: docs
+    - url: https://github.com/stackabletech/trino-operator.git
+      branches: main
+      start_path: docs
+    - url: https://github.com/stackabletech/zookeeper-operator.git
+      branches: main
+      start_path: docs
+
+ui:
+  bundle:
+    url: https://repo.stackable.tech/repository/misc/antora-ui-bundle.zip
+    snapshot: true
+  supplemental_files: /usr/local/share/.config/yarn/global/node_modules/@antora/lunr-extension/supplemental_ui
+
+antora:
+  extensions:
+    - '@antora/lunr-extension'
+
+asciidoc:
+  attributes:
+    base-repo: https://github.com/stackabletech