docs: move manager docs out of config options (#5410)

docs/usage/configuration-options.md

lib/config/definitions.ts

lib/manager/ansible/readme.md

lib/manager/bazel/readme.md

lib/manager/cdnurl/readme.md

lib/manager/github-actions/readme.md

lib/manager/gomod/readme.md

lib/manager/gradle-wrapper/readme.md

lib/manager/helm-requirements/readme.md

lib/manager/helm-values/readme.md

lib/manager/kubernetes/readme.md

lib/manager/npm/readme.md

lib/manager/nuget/readme.md

lib/manager/pip_requirements/readme.md

lib/manager/sbt/readme.md

lib/manager/swift/readme.md

lib/manager/terraform/readme.md

test/website-docs.spec.ts