[SPARK-12093][SQL] Fix the error of comment in DDLParser

Author: Yadong Qi <qiyadong2010@gmail.com>

Closes #10096 from watermen/patch-1.

sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/DDLParser.scala

@@ -66,15 +66,15 @@ class DDLParser(parseQuery: String => LogicalPlan)
   protected def start: Parser[LogicalPlan] = ddl
 
   /**
-   * `CREATE [TEMPORARY] TABLE avroTable [IF NOT EXISTS]
+   * `CREATE [TEMPORARY] TABLE [IF NOT EXISTS] avroTable
    * USING org.apache.spark.sql.avro
    * OPTIONS (path "../hive/src/test/resources/data/files/episodes.avro")`
    * or
-   * `CREATE [TEMPORARY] TABLE avroTable(intField int, stringField string...) [IF NOT EXISTS]
+   * `CREATE [TEMPORARY] TABLE [IF NOT EXISTS] avroTable(intField int, stringField string...)
    * USING org.apache.spark.sql.avro
    * OPTIONS (path "../hive/src/test/resources/data/files/episodes.avro")`
    * or
-   * `CREATE [TEMPORARY] TABLE avroTable [IF NOT EXISTS]
+   * `CREATE [TEMPORARY] TABLE [IF NOT EXISTS] avroTable
    * USING org.apache.spark.sql.avro
    * OPTIONS (path "../hive/src/test/resources/data/files/episodes.avro")`
    * AS SELECT ...