Review fix

Author: gaborgsomogyi

sql/core/src/main/scala/org/apache/spark/sql/DataFrameWriter.scala

@@ -592,7 +592,7 @@ final class DataFrameWriter[T] private[sql](ds: Dataset[T]) {
    * <li>`sep` (default `,`): sets the single character as a separator for each
    * field and value.</li>
    * <li>`quote` (default `"`): sets the single character used for escaping quoted values where
-   * the separator can be part of the value. If and empty string is set, it uses `u0000`
+   * the separator can be part of the value. If an empty string is set, it uses `u0000`
    * (null character).</li>
    * <li>`escape` (default `\`): sets the single character used for escaping quotes inside
    * an already quoted value.</li>