Update README.md

Signed-off-by: Eric Zhao <sczyh16@gmail.com>

Author: sczyh30

README.md

@@ -1 +1,48 @@
-# OpenSergo Java SDK
+<img src="https://user-images.githubusercontent.com/9434884/197435179-bbda0a82-6bae-485e-ac1a-490fee91a002.png" alt="OpenSergo Logo" width="50%">
+
+# OpenSergo Java SDK
+
+[![OpenSergo Java SDK CI](https://github.com/opensergo/opensergo-java-sdk/actions/workflows/ci.yml/badge.svg)](https://github.com/opensergo/opensergo-java-sdk/actions/workflows/ci.yml)
+[![Maven Central](https://img.shields.io/maven-central/v/io.opensergo/opensergo-java-sdk.svg?label=Maven%20Central)](https://search.maven.org/search?q=g:%22io.opensergo%22%20AND%20a:%22opensergo-java-sdk%22)
+[![License](https://img.shields.io/badge/license-Apache%202-4EB1BA.svg)](https://www.apache.org/licenses/LICENSE-2.0.html)
+
+## Introduction
+
+## Documentation
+
+See the [OpenSergo Website](https://opensergo.io/) for the official website of OpenSergo.
+
+See the [中文文档](https://opensergo.io/zh-cn/) for document in Chinese.
+
+## Quick Start
+
+1. Add dependency in Maven `pom.xml`:
+
+```xml
+<!-- replace here with the latest version -->
+<dependency>
+    <groupId>io.opensergo</groupId>
+    <artifactId>opensergo-java-sdk</artifactId>
+    <version>0.1.0-alpha</version>
+</dependency>
+```
+
+2. Subscribe data from OpenSergo control plane:
+
+```java
+// 1. Create client with remote host and port of OpenSergo control plane
+OpenSergoClient client = new OpenSergoClient(host, port);
+// 2. Start the OpenSergo client.
+client.start();
+
+// 3. Subscribe the config of the target (namespace, appName, kind)
+client.subscribeConfig(new SubscribeKey("default", "my-service", configKind),
+    new OpenSergoConfigSubscriber() {
+        @Override
+        public boolean onConfigUpdate(SubscribeKey subscribeKey, Object dataList) {
+            // Handle received config here
+            System.out.println("key: " + subscribeKey + ", data: " + dataList);
+            return true;
+        }
+    });
+```