docs: update README banner to v2.1.x announcement

Co-Authored-By: Claude Sonnet 4.6 (1M context) <noreply@anthropic.com>

Author: Devesh-Skyflow

README.md

@@ -1,11 +1,6 @@
 # Skyflow Java
 
-> **This is the current, recommended version of the Skyflow Java SDK.**
-> V2 (latest: **2.0.4**) brings flexible auth, multi-vault support, builder patterns, native data types, and rich error diagnostics.
->
-> Migrating from v1? See the **[Migration Guide](docs/migrate_to_v2.md)** for step-by-step instructions. V1 is in maintenance mode and will reach **End of Life on October 31, 2026**.
->
-> **Coming soon:** v2.1.x will include public interface nomenclature improvements and additional deprecation signals. See [release notes](https://github.com/skyflowapi/skyflow-java/releases) for details.
+> **Java V2.1.x IS NOW AVAILABLE:** A new, improved version of the Skyflow SDK is ready with flexible authentication, multi-vault support, builder patterns, and richer error diagnostics. V1 is in maintenance mode (security patches only) and will reach End of Life on October 31, 2026. We recommend upgrading to v2 — see the **[Migration Guide](docs/migrate_to_v2.md)** for step-by-step instructions.
 
 The Skyflow Java SDK is designed to help with integrating Skyflow into a Java backend.