Downgrade markdownlint-rule-relative-links to v3 to avoid yarn errors with incompatible engines (#50625)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/50625

Changelog: [internal]

This fixes yarn install errors coming from repositories other than `react-native` where `--ignore-engines` isn't specified. This was caused by `markdownlint-rule-relative-links` requiring Node.js >= v22 when we're using v20 in most cases.

Fixes https://github.com/react-native-community/docker-android/actions/runs/14380730414/job/40323632337?pr=234

Reviewed By: cortinico

Differential Revision: D72789007

fbshipit-source-id: 2c0b161af8be8d37bf57a7ea9cc22023434d4cb2