In general, every website needs assets: images, stylesheets, favicons and etc. In such cases, you can create a directory named `static` at the root of your project. Every file you put into that directory will be copied into the the root of the generated `build` folder with the directory hierarchy preserved. E.g. if you add a file named `sun.jpg` to the static folder, it’ll be copied to `build/sun.jpg`.
You can reference assets from the `static` folder in your code. You could use hardcoded absolute paths, i.e. starting with a slash /, but remember to include the `baseUrl` if it is not `/`. However, this will break if you change your `baseUrl` in the config.
Thanks to MDX, you can also use `useBaseUrl` utility function in Markdown files! You'd have to use `<img>` tags instead of the Markdown image syntax though. The syntax is exactly the same as in JSX.