Merge pull request #2 from meshplus/docs/update-readme

docs(readme):update README.md

README.md

@@ -1,12 +1,12 @@
-Go Bitxhub Client
+Java Bitxhub Client
 =====
 
 This SDK enables Java developers to build solutions that interact with BitXHub.
 
 ## Prepare
 You need to have the following dependencies installed on your machine.
 - [__Java8+__](https://www.oracle.com/java/technologies/javase-downloads.html)
-- [__Maven3.6+__](https://maven.apache.org/download.cgi)
+- [__Maven3.3+__](https://maven.apache.org/download.cgi)
 
 ## Getting started
 Obtain the client SDK packages for BitXHub.
@@ -23,10 +23,6 @@ Then you can get the `java-bitxhub-client-0.1.0-jar-with-dependencies.jar` in th
 
 You're good to go, happy coding! Check out the examples for usage demonstrations.
 
-### Documentation
-
-SDK documentation can be viewed at [JavaDoc](https://github.com/meshplus/java-bitxhub-client/wiki/Java-SDK%E4%BD%BF%E7%94%A8%E6%96%87%E6%A1%A3).
-
 ### Examples
 
 - [RPC Test](src/test/java/cn/dmlab/bitxhub/RPCTest.java): Basic example that uses SDK to query and execute transaction.
@@ -35,11 +31,16 @@ SDK documentation can be viewed at [JavaDoc](https://github.com/meshplus/java-bi
 - [Subscribe Test](src/test/java/cn/dmlab/bitxhub/SubscribeTest.java): An example that uses SDK to subscribe the block event.
 - [Sync Test](src/test/java/cn/dmlab/bitxhub/SyncTest.java): An example that uses SDK to sync the merkle wrapper.
 - [Appchain Test](src/test/java/cn/dmlab/bitxhub/AppchainTest.java): Basic example that uses SDK to register and adult appchain. 
+
+### Documentation
+
+SDK documentation can be viewed at [JavaDoc](https://github.com/meshplus/java-bitxhub-client/wiki/Java-SDK%E4%BD%BF%E7%94%A8%E6%96%87%E6%A1%A3).
+
 ## Client SDK
 You should start [BitXHub](https://github.com/meshplus/bitxhub) before using SDK.
 
 ### Running the test
-Obtain the client SDK packages for BitXHub.
+
 ```shell script
 # In the BitXHub SDK Java directory
 cd java-bitxhub-client/