Fix: typos and update links in contribute.md and index.js

[youyyytrok]

This PR addresses a few small but important changes:

1. contribute.md:

   • Updated broken links:
     • Changed the Ephemera link from https://github.com/xmtp-labs to https://github.com/ephemeraHQ.
   • Fixed a typo: meerged → merged.

2. index.js:

   • Corrected a minor formatting issue: updated md:text-x to md:text-xl for better readability.

[vercel]

@youyyytrok is attempting to deploy a commit to the Ephemera Team on Vercel.

A member of the Team first needs to authorize it.

[youyyytrok]

Hi @jhaaaa , Could you please take a look at my pull request when you get a chance? Thanks in advance for your time. 🙌