Issue on docs

Path:/zh-CN/docs/sql-manual/sql-functions/aggregate-functions/min-by

+------+------+------+------+
| k1 | k2 | k3 | k4 |
+------+------+------+------+
| 0 | 3 | 2 | 100 |
| 1 | 2 | 3 | 4 |
| 4 | 3 | 2 | 1 |
| 3 | 4 | 2 | 1 |
+------+------+------+------+

select min_by(k1, k4) from tbl;

+--------------------+
| min_by(`k1`, `k4`) |
+--------------------+
| 4 |
+--------------------+

如何得出最小的k4对应的最小的k1，如上就是得出3？