Update cluster demo README and remove unused demo

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

sentinel-demo/sentinel-demo-cluster/sentinel-demo-cluster-embedded/README.md

@@ -0,0 +1,6 @@
+# Sentinel Cluster Embedded Mode Demo
+
+This demo demonstrates how to configure data source for cluster rules and configuration
+in **embedded mode**. You can start multiple `ClusterDemoApplication` instances and do cluster assignment in Sentinel dashboard or via dynamic data source.
+
+See [DemoClusterInitFunc](https://github.com/alibaba/Sentinel/blob/master/sentinel-demo/sentinel-demo-cluster/sentinel-demo-cluster-embedded/src/main/java/com/alibaba/csp/sentinel/demo/cluster/init/DemoClusterInitFunc.java) for a sample of dynamic configuration.

sentinel-demo/sentinel-demo-cluster/sentinel-demo-cluster-embedded/src/main/java/com/alibaba/csp/sentinel/demo/cluster/ClusterClientDemo.java

@@ -1,62 +0,0 @@
-/*
- * Copyright 1999-2018 Alibaba Group Holding Ltd.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-package com.alibaba.csp.sentinel.demo.cluster;
-
-import com.alibaba.csp.sentinel.Entry;
-import com.alibaba.csp.sentinel.EntryType;
-import com.alibaba.csp.sentinel.SphU;
-import com.alibaba.csp.sentinel.cluster.ClusterStateManager;
-import com.alibaba.csp.sentinel.init.InitExecutor;
-import com.alibaba.csp.sentinel.slots.block.BlockException;
-
-/**
- * <p>Run this demo with the following args: -Dproject.name=appA</p>
- * <p>You need a token server running already.</p>
- *
- * @author Eric Zhao
- */
-public class ClusterClientDemo {
-
-    public static void main(String[] args) {
-        InitExecutor.doInit();
-
-        // Manually schedule the cluster mode to client.
-        // In common, we need a scheduling system to modify the cluster mode automatically.
-        // Command HTTP API: http://<ip>:<port>/setClusterMode?mode=<xxx>
-        ClusterStateManager.setToClient();
-
-        String resourceName = "cluster-demo-entry";
-
-        // Assume we have a cluster flow rule for `demo-resource`: QPS = 5 in AVG_LOCAL mode.
-        for (int i = 0; i < 10; i++) {
-            tryEntry(resourceName);
-        }
-    }
-
-    private static void tryEntry(String res) {
-        Entry entry = null;
-        try {
-            entry = SphU.entry(res, EntryType.IN, 1, "abc", "def");
-            System.out.println("Passed");
-        } catch (BlockException ex) {
-            ex.printStackTrace();
-        } finally {
-            if (entry != null) {
-                entry.exit();
-            }
-        }
-    }
-}