Add info for additional languages to customizing documentation #883

Job	Run time
build-docker (internet.nl, docker/Dockerfile, app)	3m 15s
build-docker (unbound, docker/Dockerfile, unbound)	1m 36s
build-docker (linttest, docker/Dockerfile, linttest)	4m 26s
build-docker (test-runner, docker/test-runner.Dockerfile)	6m 26s
build-docker (webserver, docker/webserver.Dockerfile)	1m 49s
build-docker (rabbitmq, docker/rabbitmq.Dockerfile)	1m 30s
build-docker (grafana, docker/grafana.Dockerfile)	2m 0s
build-docker (prometheus, docker/prometheus.Dockerfile)	1m 54s
build-docker (cron, docker/cron.Dockerfile)	1m 31s
lint/check	3m 17s
docs	1s
integration-test	5m 25s
development-environment-test	4m 26s
test	4m 17s
	41m 53s

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