Merge branch 'master' into cron-pod-affinity

docs/administrator.md

docs/developer.md

docs/gsoc-2019/ideas.md

docs/index.md

docs/operator-ui.md

docs/quickstart.md

docs/reference/cluster_manifest.md

docs/reference/command_line_and_environment.md

docs/reference/operator_parameters.md

docs/user.md

manifests/postgres-operator.yaml

mkdocs.yml