Update centres.json with new centre details and correct state names

[ayushedith]

Data Cleanup: ISRO Centres JSON Revamp

✅ What’s Improved

• 🧱 Consistent field names: Standardized "Place" and "State" to lowercase ("place", "state") for cleaner formatting and consistency across the file.
• 🧽 Duplicate removed: The New Space India Limited (NSIL) entry appeared twice — that’s now been fixed.
• 🔠 Alphabetical sorting: Centres are now neatly sorted by state, and then by city, making it easier to scan and search through.
• 🌍 Corrected state names: Cleaned up some inconsistencies like "Andaman and Nicobar" → "Andaman and Nicobar Islands" for accuracy.
• 💬 Comment-ready structure: The JSON is now formatted and organized in a way that’s easy to extend or annotate — perfect for collaboration.