[ci-install] Move documentation to bob.devtools user guide

ci-install/README.md

ci-install/linux/README.md

ci-install/macos/README.rst

ci-install/macos/scripts/admin-install.sh

ci-install/macos/scripts/datetime.sh

ci-install/macos/scripts/idiap-host.sh

ci-install/macos/scripts/install-gitlab-runner.sh

ci-install/macos/scripts/install-homebrew.sh

ci-install/macos/scripts/install-sdk.sh

ci-install/macos/scripts/setup-paths.sh

ci-install/macos/scripts/system-update.sh

ci-install/macos/scripts/xcode-cli-tools.sh