Document: explain what syntax is supported

[sapphi-red]

It would be nice if there's a explanation which syntax is supported on the README so that I can link it from a document (e.g. vite).

Examples from other libraries:

• https://github.com/micromatch/picomatch?tab=readme-ov-file#globbing-features
• https://github.com/micromatch/micromatch?tab=readme-ov-file#matching-features
• https://github.com/micromatch/micromatch?tab=readme-ov-file#extended-globbing
• https://github.com/isaacs/minimatch?tab=readme-ov-file#features
• https://github.com/mrmlnc/fast-glob?tab=readme-ov-file#pattern-syntax
• https://github.com/isaacs/node-glob?tab=readme-ov-file#glob-primer