docs: add Capacitor version compatibility table to README

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: riderx

README.md

@@ -173,3 +173,14 @@ See [`CONTRIBUTING.md`](./CONTRIBUTING.md).
 ## Contributors
 
 Made possible by the [Capacitor community](https://github.com/ionic-team/capacitor/graphs/contributors). 💖
+
+## Compatibility
+
+| Plugin version | Capacitor compatibility | Maintained |
+| -------------- | ----------------------- | ---------- |
+| v8.\*.\*       | v8.\*.\*                | ✅          |
+| v7.\*.\*       | v7.\*.\*                | On demand   |
+| v6.\*.\*       | v6.\*.\*                | ❌          |
+| v5.\*.\*       | v5.\*.\*                | ❌          |
+
+> **Note:** The major version of this plugin follows the major version of Capacitor. Use the version that matches your Capacitor installation (e.g., plugin v8 for Capacitor 8). Only the latest major version is actively maintained.