Nowadays, this repo is mostly the open collection of the company's Dockerfiles that are used by Parity in different ways. If you work on a Polkadot SDK-based project, you could be interested in our CI image (ci-unified) in the dockerfiles directory.
scripts mostly is a legacy name. Yes, this repo contains some scripts, but they are kept here for historical reasons. We are not actively maintaining them. If you are looking for something specific, please, open an issue and we will try to help you.
ci-unified image for most of our CI pipelines (including the pipelines for Polkadot SDK-based/Polkadot SDK-related projects and Polkadot SDK itself). You can find more information about the image in the dockerfiles/ci-unified directory.