[Minor] Update README.md (apache#5571)

### What changes were proposed in this pull request?

Update the feature list to be more up-to-date and match the website.

### Why are the changes needed?

So people know what Gravitino does.

### Does this PR introduce _any_ user-facing change?

No

### How was this patch tested?

N/A

README.md

@@ -35,11 +35,12 @@ Apache Gravitino is a high-performance, geo-distributed, and federated metadata
 ![Gravitino Architecture](docs/assets/gravitino-architecture.png)
 
 Gravitino aims to provide several key features:
-
-* Single source of truth for multi-regional data with geo-distributed architecture support.
-* Unified data and AI asset management for both users and engines.
-* Security in one place, centralizing the security for different sources.
-* Built-in data management and data access management.
+* Unified Metadata Management: Gravitino provides a unified model and API to manage different types of metadata, including relational (e.g., Hive, MySQL) and file-based (e.g., HDFS, S3) metadata sources.
+* End-to-End Data Governance: Gravitino offers a unified governance layer for managing metadata with features like access control, auditing, and discovery.
+* Direct Metadata Management: Gravitino connects directly to metadata sources via connectors, ensuring changes are instantly reflected between Gravitino and the underlying systems.
+* Geo-Distribution Support: Gravitino enables deployment across multiple regions or clouds, allowing instances to share metadata for a global cross-region view.
+* Multi-Engine Support: Gravitino supports query engines enabling metadata access without modifying SQL dialects.
+* AI Asset Management (WIP): Gravitino is expanding to manage both data and AI assets, with support for AI models and features currently in development.
 
 ## Contributing to Apache Gravitino