Support for MD053: Link and image reference definitions should be needed

Hi,

I'm trying to lint my markdown file and catch a common mistake: I make a typo in the reference e.g.:

```markdown

This is [a link].

[a Iink]: http:/...
```

Currently `mado` doesn't see an issue with it `mado check` but other tools flag it (e.g. `npx markdownlint-cli2`) as [`error MD053/link-image-reference-definitions Link and image reference definitions should be needed Unused link or image reference definition:...`](https://github.com/DavidAnson/markdownlint/blob/main/doc/md053.md)

Of course I'd prefer to stay with mado as I'm really enjoying the experience 😊

Thank you and have a nice day! 👋

Start with the mado check entry point and reproduce the example using the unused reference definition. Compare the reported behavior with the MD053 description linked in the issue. Done means mado check reports the unused link or image reference definition while preserving normal reference usage.

Do mô hình lập chỉ mục viết ra từ nội dung của issue.