See https://docusaurus.io/docs/markdown-features/links
Using relative file paths (with .md extensions) instead of relative URL links provides the following benefits:
- Links will keep working on the GitHub interface and many Markdown editors
- You can customize the files' slugs without having to update all the links
- Moving files around the folders can be tracked by your editor, and some editors may automatically update file links
- A versioned doc will link to another doc of the exact same version
- Relative URL links are very likely to break if you update the trailingSlash config