[Doc] Fix MV Partition functions (StarRocks#30132)

Signed-off-by: 絵空事スピリット <[email protected]>

docs/sql-reference/sql-statements/data-definition/CREATE MATERIALIZED VIEW.md

@@ -231,7 +231,8 @@ The partitioning strategy of the asynchronous materialized view. As for the curr
 Valid values:
 
 - `column_name`: The name of the column used for partitioning. The expression `PARTITION BY dt` means to partition the materialized view according to the `dt` column.
-- date_trunc function: The function used to truncate the time unit. `PARTITION BY date_trunc("MONTH", 'dt')` means that the `dt` column is truncated to month as the unit for partitioning. The date_trunc function supports truncating time to units including `YEAR`, `MONTH`, `DAY`, `HOUR`, and `MINUTE`. From v3.1 onwards, you can further use time_slice or date_slice functions to convert the given time into the beginning or end of a time interval based on the specified time granularity, for example, `PARTITION BY date_trunc("MONTH", time_slice(`dt`, INTERVAL 7 DAY))` where time_slice's or date_slice's type must be of finer granularity than `date_trunc`'s type.
+- date_trunc function: The function used to truncate the time unit. `PARTITION BY date_trunc("MONTH", dt)` means that the `dt` column is truncated to month as the unit for partitioning. The date_trunc function supports truncating time to units including `YEAR`, `MONTH`, `DAY`, `HOUR`, and `MINUTE`.
+- time_slice or date_slice functions: From v3.1 onwards, you can further use these functions to convert the given time into the beginning or end of a time interval based on the specified time granularity, for example, `PARTITION BY date_trunc("MONTH", time_slice(dt, INTERVAL 7 DAY))` where time_slice and date_slice must have a finer granularity than date_trunc. You can use them to specify a GROUP BY column with a finer granularity than that of the partitioning key, for example, `GROUP BY time_slice(dt, INTERVAL 1 MINUTE) PARTITION BY date_trunc('DAY', ts)`.
 
 If this parameter is not specified, no partitioning strategy is adopted by default.