[SPARK-18752][SQL] Follow-up: add scaladoc explaining isSrcLocal arg.

Author: Marcelo Vanzin <vanzin@cloudera.com>

Closes #16257 from vanzin/SPARK-18752.2.

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/catalog/ExternalCatalog.scala

@@ -114,6 +114,12 @@ abstract class ExternalCatalog {
 
   def listTables(db: String, pattern: String): Seq[String]
 
+  /**
+   * Loads data into a table.
+   *
+   * @param isSrcLocal Whether the source data is local, as defined by the "LOAD DATA LOCAL"
+   *                   HiveQL command.
+   */
   def loadTable(
       db: String,
       table: String,
@@ -122,6 +128,12 @@ abstract class ExternalCatalog {
       holdDDLTime: Boolean,
       isSrcLocal: Boolean): Unit
 
+  /**
+   * Loads data into a partition.
+   *
+   * @param isSrcLocal Whether the source data is local, as defined by the "LOAD DATA LOCAL"
+   *                   HiveQL command.
+   */
   def loadPartition(
       db: String,
       table: String,