Mention React Auth Workflow in dev doc

[huayunh]

Added a section in the Dev Doc to direct the traffic to GitHub readmes

To Test

• yarn && yarn start:reactdev
• The new page is located at http://localhost:3000/workflows/user-auth

[github-actions[bot]]

Visit the preview URL for this PR (updated for commit 12ff839):

https://blui-react-docs--pr807-feature-react-workfl-2rleqzga.web.app

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