Perform some documentation cleanup

docs/examples/gitlab.md

docs/executors/kubernetes.md

docs/executors/shell.md

docs/executors/ssh.md

docs/executors/virtualbox.md

docs/faq/README.md

docs/install/autoscaling.md

docs/install/bleeding-edge.md

docs/install/docker.md

docs/install/freebsd.md

docs/install/index.md

docs/install/kubernetes.md

docs/install/linux-manually.md

docs/install/linux-repository.md

docs/install/osx.md

docs/install/windows.md

docs/monitoring/README.md

docs/release_process/README.md

docs/shells/README.md