[doc] update readme

README.md

@@ -44,14 +44,14 @@
 <dependency>
    <groupId>org.dromara.stream-query</groupId>
    <artifactId>stream-plugin-mybatis-plus</artifactId>
-   <version>x.x.x</version>
+   <version>2.1.0-alpha</version>
 </dependency>
 <!-- 可单独引入 -->
 <!-- https://mvnrepository.com/artifact/org.dromara/stream-core -->
 <dependency>
   <groupId>org.dromara.stream-query</groupId>
   <artifactId>stream-core</artifactId>
-  <version>x.x.x</version>
+  <version>2.1.0-alpha</version>
 </dependency>
 ```
 

stream-core/checkstyle/license-header.txt

@@ -0,0 +1,16 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You 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.
+ */