Update quickstart.mdx

[u0uo]

Fixed a typo on line 155.

Closes #

💸 TL;DR

Typo corrected on line 155.

📜 Details

Design Doc

Jira

🧪 Testing Steps / Validation

✅ Checks

• [ ] CI tests (if present) are passing
• [ ] Adheres to code style for repo
• [ ] Contributor License Agreement (CLA) completed if not a Reddit employee