correct tiny comment error

Author: Chen Chao <crazyjvm@gmail.com>

Closes #928 from CrazyJvm/patch-8 and squashes the following commits:

144328b [Chen Chao] correct tiny comment error

core/src/main/scala/org/apache/spark/SparkContext.scala

@@ -76,8 +76,8 @@ class SparkContext(config: SparkConf) extends Logging {
    * :: DeveloperApi ::
    * Alternative constructor for setting preferred locations where Spark will create executors.
    *
-   * @param preferredNodeLocationData used in YARN mode to select nodes to launch containers on. Ca
-   * be generated using [[org.apache.spark.scheduler.InputFormatInfo.computePreferredLocations]]
+   * @param preferredNodeLocationData used in YARN mode to select nodes to launch containers on.
+   * Can be generated using [[org.apache.spark.scheduler.InputFormatInfo.computePreferredLocations]]
    * from a list of input files or InputFormats for the application.
    */
   @DeveloperApi