[jvm-packages] [doc] Update install doc for JVM packages (#6051)

doc/jvm/index.rst

@@ -65,6 +65,8 @@ This will check out the latest stable version from the Maven Central.
 
 For the latest release version number, please check `here <https://github.com/dmlc/xgboost/releases>`_.
 
+To enable the GPU algorithm (``tree_method='gpu_hist'``), use artifacts ``xgboost4j-gpu_2.12`` and ``xgboost4j-spark-gpu_2.12`` instead (note the ``gpu`` suffix).
+
 .. note:: Using Maven repository hosted by the XGBoost project
 
   There may be some delay until a new release becomes available to Maven Central. If you would like to access the latest release immediately, add the Maven repository hosted by the XGBoost project:
@@ -83,6 +85,11 @@ For the latest release version number, please check `here <https://github.com/dm
 
     resolvers += "XGBoost4J Release Repo" at "https://s3-us-west-2.amazonaws.com/xgboost-maven-repo/release/"
 
+.. note:: Windows not supported in the JVM package
+
+  Currently, XGBoost4J-Spark does not support Windows platform, as the distributed training algorithm is inoperational for Windows. Please use Linux or MacOS.
+
+
 Access SNAPSHOT version
 -----------------------
 
@@ -141,9 +148,8 @@ The SNAPSHOT JARs are hosted by the XGBoost project. Every commit in the ``maste
 
 You can browse the file listing of the Maven repository at https://s3-us-west-2.amazonaws.com/xgboost-maven-repo/list.html.
 
-.. note:: Windows not supported by published JARs
+To enable the GPU algorithm (``tree_method='gpu_hist'``), use artifacts ``xgboost4j-gpu_2.12`` and ``xgboost4j-spark-gpu_2.12`` instead (note the ``gpu`` suffix).
 
-  The published JARs from the Maven Central and GitHub currently only supports Linux and MacOS. Windows users should consider building XGBoost4J / XGBoost4J-Spark from the source. Alternatively, checkout pre-built JARs from `criteo-forks/xgboost-jars <https://github.com/criteo-forks/xgboost-jars>`_.
 
 Installation from source
 ========================

jvm-packages/README.md

@@ -18,78 +18,94 @@ You can find more about XGBoost on [Documentation](https://xgboost.readthedocs.o
 
 ## Add Maven Dependency
 
-XGBoost4J, XGBoost4J-Spark, etc. in maven repository is compiled with g++-4.8.5  
+XGBoost4J, XGBoost4J-Spark, etc. in maven repository is compiled with g++-4.8.5.
 
 ### Access release version
 
-<b>maven</b> 
+<b>Maven</b>
 
 ```
 <dependency>
     <groupId>ml.dmlc</groupId>
     <artifactId>xgboost4j_2.12</artifactId>
     <version>latest_version_num</version>
 </dependency>
-``` 
-
-<b>sbt</b> 
+<dependency>
+    <groupId>ml.dmlc</groupId>
+    <artifactId>xgboost4j-spark_2.12</artifactId>
+    <version>latest_version_num</version>
+</dependency>
+```
+
+<b>sbt</b>
 ```sbt
- "ml.dmlc" %% "xgboost4j" % "latest_version_num"
-``` 
+libraryDependencies ++= Seq(
+  "ml.dmlc" %% "xgboost4j" % "latest_version_num",
+  "ml.dmlc" %% "xgboost4j-spark" % "latest_version_num"
+)
+```
 
 For the latest release version number, please check [here](https://github.com/dmlc/xgboost/releases).
 
-if you want to use `xgboost4j-spark`, you just need to replace xgboost4j with `xgboost4j-spark`
+To enable the GPU algorithm (`tree_method='gpu_hist'`), use artifacts `xgboost4j-gpu_2.12` and `xgboost4j-spark-gpu_2.12` instead.
 
 ### Access SNAPSHOT version
 
-You need to add github as repo:
+First add the following Maven repository hosted by the XGBoost project:
 
-<b>maven</b>:
+<b>Maven</b>:
 
 ```xml
 <repository>
-  <id>GitHub Repo</id>
-  <name>GitHub Repo</name>
-  <url>https://raw.githubusercontent.com/CodingCat/xgboost/maven-repo/</url>
+  <id>XGBoost4J Snapshot Repo</id>
+  <name>XGBoost4J Snapshot Repo</name>
+  <url>https://s3-us-west-2.amazonaws.com/xgboost-maven-repo/snapshot/</url>
 </repository>
 ```
 
 <b>sbt</b>:
- 
-```sbt 
-resolvers += "GitHub Repo" at "https://raw.githubusercontent.com/CodingCat/xgboost/maven-repo/"
+
+```sbt
+resolvers += "XGBoost4J Snapshot Repo" at "https://s3-us-west-2.amazonaws.com/xgboost-maven-repo/snapshot/"
 ```
 
-the add dependency as following:
+Then add XGBoost4J as a dependency:
 
-<b>maven</b> 
+<b>Maven</b>
 
 ```
 <dependency>
     <groupId>ml.dmlc</groupId>
     <artifactId>xgboost4j_2.12</artifactId>
-    <version>latest_version_num</version>
+    <version>latest_version_num-SNAPSHOT</version>
+</dependency>
+<dependency>
+    <groupId>ml.dmlc</groupId>
+    <artifactId>xgboost4j-spark_2.12</artifactId>
+    <version>latest_version_num-SNAPSHOT</version>
 </dependency>
-``` 
- 
-<b>sbt</b> 
+```
+
+<b>sbt</b>
 ```sbt
- "ml.dmlc" %% "xgboost4j" % "latest_version_num"
-``` 
+libraryDependencies ++= Seq(
+  "ml.dmlc" %% "xgboost4j" % "latest_version_num-SNAPSHOT",
+  "ml.dmlc" %% "xgboost4j-spark" % "latest_version_num-SNAPSHOT"
+)
+```
 
-For the latest release version number, please check [here](https://github.com/CodingCat/xgboost/tree/maven-repo/ml/dmlc/xgboost4j_2.12).
+For the latest release version number, please check [the repository listing](https://s3-us-west-2.amazonaws.com/xgboost-maven-repo/list.html).
 
-if you want to use `xgboost4j-spark`, you just need to replace xgboost4j with `xgboost4j-spark`
+To enable the GPU algorithm (`tree_method='gpu_hist'`), use artifacts `xgboost4j-gpu_2.12` and `xgboost4j-spark-gpu_2.12` instead.
 
 ## Examples
 
 Full code examples for Scala, Java, Apache Spark, and Apache Flink can
 be found in the [examples package](https://github.com/dmlc/xgboost/tree/master/jvm-packages/xgboost4j-example).
 
-**NOTE on LIBSVM Format**: 
+**NOTE on LIBSVM Format**:
 
-There is an inconsistent issue between XGBoost4J-Spark and other language bindings of XGBoost. 
+There is an inconsistent issue between XGBoost4J-Spark and other language bindings of XGBoost.
 
 When users use Spark to load trainingset/testset in LibSVM format with the following code snippet:
 
@@ -108,7 +124,7 @@ You can build/package xgboost4j locally with the following steps:
 2. Clone this repo: `git clone --recursive https://github.com/dmlc/xgboost.git`
 3. Run the following command:
   - With Tests: `./xgboost/jvm-packages/dev/build-linux.sh`
-  - Skip Tests: `./xgboost/jvm-packages/dev/build-linux.sh --skip-tests` 
+  - Skip Tests: `./xgboost/jvm-packages/dev/build-linux.sh --skip-tests`
 
 **Windows:**
 1. Ensure [Docker for Windows](https://docs.docker.com/docker-for-windows/install/) is installed.