Introducing shields-badge

🏷️ introduction shields-badge

ShieldsBadge provides Ruby badge classes through a registry and plugins. Requiring shields/badge enables lazy loading, while `ShieldsBadge.register_all` loads the built-in set eagerly. Badge calls can return Markdown or an image source URL, making the same badge definition usable in different documentation outputs.

Read the upstream README for installation and usage, or browse the project repository.