Change comment for date_format

Author: MaxGekk

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

@@ -2634,8 +2634,8 @@ object functions {
    * See [[java.time.format.DateTimeFormatter]] for valid date and time format patterns
    *
    * @param dateExpr A date, timestamp or string. If a string, the data must be in a format that
-   *                 can be cast to a timestamp, such as `yyyy-MM-dd` or `yyyy-MM-dd HH:mm:ss.SSSS`
-   * @param format A pattern `dd.MM.yyyy` would return a string like `18.03.1993`
+   *                 can be cast to a timestamp, such as `uuuu-MM-dd` or `uuuu-MM-dd HH:mm:ss.SSSS`
+   * @param format A pattern `dd.MM.uuuu` would return a string like `18.03.1993`
    * @return A string, or null if `dateExpr` was a string that could not be cast to a timestamp
    * @note Use specialized functions like [[year]] whenever possible as they benefit from a
    * specialized implementation.