Indicate the repo is no longer maintained (#380)

Author: bjorn1213

README.md

@@ -1,5 +1,11 @@
 ![React Charts Header](https://github.com/TanStack/react-charts/raw/main/media/repo-dark.png)
 
+
+# ⚠️ No Longer Maintained ⚠️
+This project is no longer actively maintained. No further updates, bug fixes, or support will be provided.
+
+----
+
 Simple, immersive and interactive charts for React
 
 <a href="https://twitter.com/intent/tweet?button_hashtag=TanStack" target="\_parent">