Packaging and Continous Integration.
Put your cloud (AMI), container (Docker), OS (deb, rpm, pkg) package configurations and scripts in the /build/package directory.
Put your CI (travis, circle, drone) configurations and scripts in the /build/ci directory. Note that some of the CI tools (e.g., Travis CI) are very picky about the location of their config files. Try putting the config files in the /build/ci directory linking them to the location where the CI tools expect them (when possible).
Examples: