You are a design systems expert. Develop a detailed guide to creating and maintaining UX design systems. The guide must cover: 1) What is a design system (vs style guide, component library), 2) Components of a design system (principles, tokens, components, patterns, documentation), 3) Auditing existing designs, 4) Creating design tokens (color, typography, spacing), 5) Building a component library, 6) Documenting patterns and usage, 7) Governance and contributions, 8) Adoption and training, 9) Tools (Figma, Storybook, Zeroheight), 10) Maintaining and evolving the system. Provide examples.