Revert "[SPARK-1105] fix site scala version error in doc"

This reverts commit d99773d5.

docs/_config.yml

@@ -5,7 +5,7 @@ markdown: kramdown
 # of Spark, Scala, and Mesos.
 SPARK_VERSION: 1.0.0-incubating-SNAPSHOT
 SPARK_VERSION_SHORT: 1.0.0
-SCALA_VERSION: "2.10.3"
+SCALA_VERSION: "2.10"
 MESOS_VERSION: 0.13.0
 SPARK_ISSUE_TRACKER_URL: https://spark-project.atlassian.net
 SPARK_GITHUB_URL: https://github.com/apache/incubator-spark