[jvm-packages] add the missing scm urls (#3589)

for some reason this part was missing in master branch????

jvm-packages/pom.xml

@@ -23,6 +23,11 @@
             <email>codingcat@apache.org</email>
         </developer>
     </developers>
+    <scm>
+        <connection>scm:git:git:/github.com/dmlc/xgboost.git</connection>
+        <developerConnection>scm:git:ssh://github.com/dmlc/xgboost.git</developerConnection>
+        <url>https://github.com/dmlc/xgboost</url>
+    </scm>
     <properties>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
         <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>