[#4048] Update README with incubator disclaimer (#4049)

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

Update README with ASF Incubator disclaimer and updated links and used
Apache Gravitino where needed.

### Why are the changes needed?

To comply with ASF policy

Fix: #4048

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

No

### How was this patch tested?

N/A - only changes a text file

README.md

@@ -17,20 +17,20 @@
   under the License.
 -->
 
-# Gravitino
-
-[![GitHub Actions Build](https://github.com/datastrato/gravitino/actions/workflows/build.yml/badge.svg)](https://github.com/datastrato/gravitino/actions/workflows/build.yml)
-[![GitHub Actions Integration Test](https://github.com/datastrato/gravitino/actions/workflows/integration-test.yml/badge.svg)](https://github.com/datastrato/gravitino/actions/workflows/integration-test.yml)
-[![License](https://img.shields.io/github/license/datastrato/gravitino)](https://github.com/datastrato/gravitino/blob/main/LICENSE)
-[![Contributors](https://img.shields.io/github/contributors/datastrato/gravitino)](https://github.com/datastrato/gravitino/graphs/contributors)
-[![Release](https://img.shields.io/github/v/release/datastrato/gravitino)](https://github.com/datastrato/gravitino/releases)
-[![Open Issues](https://img.shields.io/github/issues-raw/datastrato/gravitino)](https://github.com/datastrato/gravitino/issues)
-[![Last Committed](https://img.shields.io/github/last-commit/datastrato/gravitino)](https://github.com/datastrato/gravitino/commits/main/)
+# Apache Gravitino (incubating)
+
+[![GitHub Actions Build](https://github.com/apache/gravitino/actions/workflows/build.yml/badge.svg)](https://github.com/apache/gravitino/actions/workflows/build.yml)
+[![GitHub Actions Integration Test](https://github.com/apache/gravitino/actions/workflows/integration-test.yml/badge.svg)](https://github.com/apache/gravitino/actions/workflows/integration-test.yml)
+[![License](https://img.shields.io/github/license/apache/gravitino)](https://github.com/apache/gravitino/blob/main/LICENSE)
+[![Contributors](https://img.shields.io/github/contributors/apache/gravitino)](https://github.com/apache/gravitino/graphs/contributors)
+[![Release](https://img.shields.io/github/v/release/apache/gravitino)](https://github.com/apache/gravitino/releases)
+[![Open Issues](https://img.shields.io/github/issues-raw/apache/gravitino)](https://github.com/apache/gravitino/issues)
+[![Last Committed](https://img.shields.io/github/last-commit/apache/gravitino)](https://github.com/apache/gravitino/commits/main/)
 [![OpenSSF Best Practices](https://www.bestpractices.dev/projects/8358/badge)](https://www.bestpractices.dev/projects/8358)
 
 ## Introduction
 
-Gravitino is a high-performance, geo-distributed, and federated metadata lake. It manages the metadata directly in different sources, types, and regions. It also provides users with unified metadata access for data and AI assets.
+Apache Gravitino is a high-performance, geo-distributed, and federated metadata lake. It manages the metadata directly in different sources, types, and regions. It also provides users with unified metadata access for data and AI assets.
 
 ![Gravitino Architecture](docs/assets/gravitino-architecture.png)
 
@@ -41,15 +41,15 @@ Gravitino aims to provide several key features:
 * Security in one place, centralizing the security for different sources.
 * Built-in data management and data access management.
 
-## Contributing to Gravitino
+## Contributing to Apache Gravitino
 
 Gravitino is open source software available under the Apache 2.0 license. For information on how to contribute to Gravitino please see the [Contribution guidelines](CONTRIBUTING.md).
 
 ## Online documentation
 
 You can find the latest Gravitino documentation in the [doc folder](docs). This README file only contains basic setup instructions.
 
-## Building Gravitino
+## Building Apache Gravitino
 
 You can build Gravitino using Gradle. Currently you can build Gravitino on Linux and macOS, Windows isn't supported.
 
@@ -81,7 +81,7 @@ For the details of building and testing Gravitino, please see [How to build Grav
 
 ## Quick start
 
-### Configure and start the Gravitino server
+### Configure and start the Apache Gravitino server
 
 If you already have a binary distribution package, go to the directory of the decompressed package.
 
@@ -108,7 +108,7 @@ Alternatively, to run the Gravitino server in frontend, please run:
 
 And press `CTRL+C` to stop the Gravitino server.
 
-### Using Trino with Gravitino
+### Using Trino with Apache Gravitino
 
 Gravitino provides a Trino connector to access the metadata in Gravitino. To use Trino with Gravitino, please follow the [trino-gravitino-connector doc](docs/trino-connector/index.md).
 
@@ -122,4 +122,8 @@ Gravitino provides a Trino connector to access the metadata in Gravitino. To use
 
 Gravitino is under the Apache License Version 2.0, See the [LICENSE](LICENSE) for the details.
 
-<sub>Apache®, Apache Hadoop&reg;, Apache Hive&trade;, Apache Iceberg&trade;, Apache Kafka&reg;, Apache Spark&trade;, Apache Submarine&trade;, Apache Thrift&trade; and Apache Zeppelin&trade; are either registered trademarks or trademarks of the Apache Software Foundation in the United States and/or other countries.</sub>
+## ASF Incubator disclaimer
+
+Apache Gravitino is an effort undergoing incubation at The Apache Software Foundation (ASF), sponsored by the Apache Incubator. Incubation is required of all newly accepted projects until a further review indicates that the infrastructure, communications, and decision making process have stabilized in a manner consistent with other successful ASF projects. While incubation status is not necessarily a reflection of the completeness or stability of the code, it does indicate that the project has yet to be fully endorsed by the ASF.
+
+<sub>Apache®, Apache Gravitino&trade;, Apache Hadoop&reg;, Apache Hive&trade;, Apache Iceberg&trade;, Apache Kafka&reg;, Apache Spark&trade;, Apache Submarine&trade;, Apache Thrift&trade; and Apache Zeppelin&trade; are either registered trademarks or trademarks of the Apache Software Foundation in the United States and/or other countries.</sub>