Revise README to include links to docs for better guidance (#2611)

Author: josh-wong

README.md

@@ -11,9 +11,21 @@ ScalarDB is a universal HTAP engine. It achieves ACID transactions and real-time
   <a href='https://www.youtube.com/watch?v=lW6nCEJV-gs' target="_blank"><img src='docs/images/scalardb-video-preview.png' width='70%'></a>
 </p>
 
-## Docs
+To learn more, see [ScalarDB Overview](https://scalardb.scalar-labs.com/docs/latest/overview).
 
-See our [User Documentation](https://scalardb.scalar-labs.com/docs/latest/).
+## Quickstart
+
+1. Start running transactions.
+   - **Get started with ScalarDB Core:** To set up a basic application by using Java, see [Getting Started with ScalarDB](https://scalardb.scalar-labs.com/docs/latest/getting-started-with-scalardb).
+   - **Get started with ScalarDB Cluster (for enterprise customers):** To set up a basic application that uses ScalarDB Cluster through the Java API, see [Getting Started with ScalarDB Cluster](https://scalardb.scalar-labs.com/docs/latest/scalardb-cluster/getting-started-with-scalardb-cluster).
+2. To set up and run various samples instances, see the [list of ScalarDB sample applications](https://scalardb.scalar-labs.com/docs/latest/scalardb-samples).
+3. Learn about the [configurations for ScalarDB Core](https://scalardb.scalar-labs.com/docs/latest/configurations) and the [configurations for ScalarDB Cluster](https://scalardb.scalar-labs.com/docs/latest/scalardb-cluster/scalardb-cluster-configurations).
+4. Learn about features, such as:
+   - [User authentication/authorization](https://scalardb.scalar-labs.com/docs/latest/scalardb-cluster/scalardb-auth-with-sql) (for enterprise customers)
+   - [Attribute-based access control](https://scalardb.scalar-labs.com/docs/latest/scalardb-cluster/authorize-with-abac) (for enterprise customers)
+   - [Vector search](https://scalardb.scalar-labs.com/docs/latest/scalardb-cluster/getting-started-with-vector-search) (for enterprise customers)
+
+For additional documentation, visit [ScalarDB Documentation](https://scalardb.scalar-labs.com/docs/latest/).
 
 ## Install