Fix typo

[MonkeyKing44]

✏️ Fix Typo in reference.mdx

🛠️ Description

This PR corrects a small typo in subproviders/docs/reference.mdx:

• Fixed "specificed" → "specified" for proper spelling.

✅ Checklist

• [x] Typo corrected
• [ ] No functional or structural changes to the documentation
• [ ] Follows project contribution guidelines

🔗 Related Issues

N/A

🔍 How to Review

1. Check the corrected spelling in reference.mdx.
2. Ensure no additional unintended changes are present.

Just a small cleanup for clarity! 🚀 Let me know if anything needs tweaking.