DX-1446 update README for ver2.2.1

Author: yujingwu

README.md

@@ -37,7 +37,7 @@ Add this dependency to your project's POM:
 <dependency>
     <groupId>cloud.artik</groupId>
     <artifactId>artikcloud-java</artifactId>
-    <version>2.2.0</version>
+    <version>2.2.1</version>
     <scope>compile</scope>
 </dependency>
 ```
@@ -47,7 +47,7 @@ Add this dependency to your project's POM:
 Add this dependency to your project's build file:
 
 ```groovy
-compile "cloud.artik:artikcloud-java:2.2.0"
+compile "cloud.artik:artikcloud-java:2.2.1"
 ```
 
 ### Others
@@ -58,7 +58,7 @@ At first generate the JAR by executing:
 
 Then manually install the following JARs:
 
-* target/artikcloud-java-2.2.0.jar
+* target/artikcloud-java-2.2.1.jar
 * target/lib/*.jar
 
 ## Getting Started