[DOC-JVM] Refactor JVM docs

doc/jvm/index.md

@@ -0,0 +1,20 @@
+XGBoost JVM Package
+===================
+[![Build Status](https://travis-ci.org/dmlc/xgboost.svg?branch=master)](https://travis-ci.org/dmlc/xgboost)
+[![GitHub license](http://dmlc.github.io/img/apache2.svg)](../LICENSE)
+
+You have find XGBoost JVM Package!
+
+Installation
+------------
+To build XGBoost4J contains two steps.
+- First type the following command to build JNI library.
+```bash
+./create_jni.sh
+```
+- Then package the libary. you can run `mvn package` in xgboost4j folder or just use IDE(eclipse/netbeans) to open this maven project and build.
+
+Contents
+--------
+* [Java Overview Tutorial](java_intro.md)
+* [Code Examples](https://github.com/dmlc/xgboost/tree/master/jvm-packages/xgboost4j-example)