Add T4 App integration

[anku255]

Summary of change

This PR adds the T4 app integration in our docs. It currently links to the supertokens-auth branch of the repo and may need changes if supertokens auth gets merged to the master branch.

Checklist

• [ ] Algolia search needs to be updated? (If there is a new sub docs project, then yes)
• [ ] Sitemap needs to be updated? (If there is a new sub docs project, then yes)
• [ ] Checked for broken links? (Run cd v2 && MODE=production npx docusaurus build)
• [ ] Changes required to the demo apps corresponding to the docs?

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