Preview of Vespa on ARM64

Vespa, a platform used internally at Yahoo, has expanded its support to include the ARM64 CPU architecture, which powers devices like AWS Graviton EC2 instances and Apple M1 MacBooks, alongside its existing support for the x86_64 architecture. This expansion comes as a preview release, with Vespa artifacts such as RPMs and container images now available for ARM64, built on CentOS Stream 8 and accessible through Fedora Copr and the GitHub Container Registry. While the ARM64 preview follows the same release cadence as the x86_64 versions, being up to four times per week based on extensive testing and production use, it is not yet production-ready, and support is offered on a best-effort basis through GitHub and Vespa Slack. Users interested in testing can use Docker or Podman to run Vespa on ARM64, with specific instructions provided for container startup in the Vespa Quick Start Guide.