README: real dedicated 'Zero Trust, Actually Implemented' section (general concept -> NetBird as the concrete implementation -> link out), host/doc count bumped to 12/16, NetBird tool bullet. netbird-zero-trust.md: dropped the LXC-provisioning tangent (not relevant to a doc about NetBird itself), added self-hosted-vs-SaaS rationale, a real Addressing table, and expanded split-DNS mechanism detail. Also genericized personal-device specifics (device types/exact split of access) that were too specific for the public repo.