Add tiflash supported pushdown for vector functions (#18901)

tiflash/tiflash-supported-pushdown-calculations.md

@@ -37,6 +37,7 @@ TiFlash 支持部分算子的下推，支持的算子如下：
 | [正则函数和算子](/functions-and-operators/string-functions.md) | `REGEXP`, `REGEXP_LIKE()`, `REGEXP_INSTR()`, `REGEXP_SUBSTR()`, `REGEXP_REPLACE()`, `RLIKE` |
 | [日期函数](/functions-and-operators/date-and-time-functions.md) | `DATE_FORMAT()`, `TIMESTAMPDIFF()`, `FROM_UNIXTIME()`, `UNIX_TIMESTAMP(int)`, `UNIX_TIMESTAMP(decimal)`, `STR_TO_DATE(date)`, `STR_TO_DATE(datetime)`, `DATEDIFF()`, `YEAR()`, `MONTH()`, `DAY()`, `EXTRACT(datetime)`, `DATE()`, `HOUR()`, `MICROSECOND()`, `MINUTE()`, `SECOND()`, `SYSDATE()`, `DATE_ADD/ADDDATE(datetime, int)`, `DATE_ADD/ADDDATE(string, int/real)`, `DATE_SUB/SUBDATE(datetime, int)`, `DATE_SUB/SUBDATE(string, int/real)`, `QUARTER()`, `DAYNAME()`, `DAYOFMONTH()`, `DAYOFWEEK()`, `DAYOFYEAR()`, `LAST_DAY()`, `MONTHNAME()`, `TO_SECONDS()`, `TO_DAYS()`, `FROM_DAYS()`, `WEEKOFYEAR()` |
 | [JSON 函数](/functions-and-operators/json-functions.md) | `JSON_LENGTH()`, `->`, `->>`, `JSON_EXTRACT()`, `JSON_ARRAY()`, `JSON_DEPTH()`, `JSON_VALID()`, `JSON_KEYS()`, `JSON_CONTAINS_PATH()`, `JSON_UNQUOTE()` |
+| [向量函数](/vector-search-functions-and-operators.md) | `VEC_L2_DISTANCE`, `VEC_COSINE_DISTANCE`, `VEC_NEGATIVE_INNER_PRODUCT`, `VEC_L1_DISTANCE`, `VEC_DIMS`, `VEC_L2_NORM`, `VEC_AS_TEXT` |
 | [转换函数](/functions-and-operators/cast-functions-and-operators.md) | `CAST(int AS DOUBLE), CAST(int AS DECIMAL)`, `CAST(int AS STRING)`, `CAST(int AS TIME)`, `CAST(double AS INT)`, `CAST(double AS DECIMAL)`, `CAST(double AS STRING)`, `CAST(double AS TIME)`, `CAST(string AS INT)`, `CAST(string AS DOUBLE), CAST(string AS DECIMAL)`, `CAST(string AS TIME)`, `CAST(decimal AS INT)`, `CAST(decimal AS STRING)`, `CAST(decimal AS TIME)`, `CAST(decimal AS DOUBLE)`, `CAST(time AS INT)`, `CAST(time AS DECIMAL)`, `CAST(time AS STRING)`, `CAST(time AS REAL)`, `CAST(json AS JSON)`, `CAST(json AS STRING)`, `CAST(int AS JSON)`, `CAST(real AS JSON)`, `CAST(decimal AS JSON)`, `CAST(string AS JSON)`, `CAST(time AS JSON)`, `CAST(duration AS JSON)` |
 | [聚合函数](/functions-and-operators/aggregate-group-by-functions.md) | `MIN()`, `MAX()`, `SUM()`, `COUNT()`, `AVG()`, `APPROX_COUNT_DISTINCT()`, `GROUP_CONCAT()` |
 | [其他函数](/functions-and-operators/miscellaneous-functions.md) | `INET_NTOA()`, `INET_ATON()`, `INET6_NTOA()`, `INET6_ATON()` |