Add spark.yarn.dist.jars to doc and fix minor issue

Author: jerryshao

docs/running-on-yarn.md

@@ -215,6 +215,13 @@ If you need a reference to the proper location to put log files in the YARN so t
     Comma-separated list of files to be placed in the working directory of each executor.
   </td>
 </tr>
+<tr>
+  <td><code>spark.yarn.dist.jars</code></td>
+  <td>(none)</td>
+  <td>
+    Comma-separated list of jars to be placed in the working directory of each executor.
+  </td>
+</tr>
 <tr>
   <td><code>spark.executor.cores</code></td>
   <td>1 in YARN mode, all the available cores on the worker in standalone mode.</td>

yarn/src/main/scala/org/apache/spark/deploy/yarn/ApplicationMasterArguments.scala

@@ -91,7 +91,7 @@ class ApplicationMasterArguments(val args: Array[String]) {
       |  --class CLASS_NAME   Name of your application's main class
       |  --primary-py-file    A main Python file
       |  --primary-r-file     A main R file
-      |  --args ARGS          Arguments to be passed to your application's main class.
+      |  --arg ARG            Argument to be passed to your application's main class.
       |                       Multiple invocations are possible, each will be passed in order.
       |  --properties-file FILE Path to a custom Spark properties file.
       """.stripMargin)

yarn/src/main/scala/org/apache/spark/deploy/yarn/config.scala

@@ -91,6 +91,10 @@ package object config {
     .stringConf
     .optional
 
+  private[spark] val JARS_TO_DISTRIBUTE = ConfigBuilder("spark.yarn.dist.jars")
+    .stringConf
+    .optional
+
   private[spark] val PRESERVE_STAGING_FILES = ConfigBuilder("spark.yarn.preserve.staging.files")
     .doc("Whether to preserve temporary files created by the job in HDFS.")
     .booleanConf
@@ -249,9 +253,4 @@ package object config {
     .stringConf
     .toSequence
     .optional
-
-  private[spark] val JARS_TO_DISTRIBUTE = ConfigBuilder("spark.yarn.dist.jars")
-    .internal
-    .stringConf
-    .optional
 }