Update website/docs/sql/scalar_func/string.md

Co-authored-by: Adrian Vogelsgesang <[email protected]>

website/docs/sql/scalar_func/string.md

@@ -50,7 +50,7 @@ Function|Return Type|Description|Example
 `right(str text, n int)`|`text`|Return last `<n>` characters in the string. When `<n>` is negative, return all but first <code>&#124;&#60;n&#62;&#124;</code> characters.|`right('abcde', 2)` → `'de'`
 `rpad(string text, length int , fill text)`|`text`|Fill up the `string` to length `length` by appending the characters `fill` (a space by default). If the `string` is already longer than `length` then it is truncated.|`rpad('hi', 5, 'xy')` → `'hixyx'`
 `rtrim(string text , characters text)`|`text`|Remove the longest string containing only characters from `characters` (a space by default) from the end of `string`.|`rtrim('testxxzx', 'xyz')` → `'test'`
-`split_part(string text, delimiter text, field int)`|`text`|Split `string` on `delimiter` and return the given field (counting from one, can be a negative value but not zero).|`split_part('abc~@~def~@~ghi', '~@~', 2)` → `'def'`
+`split_part(string text, delimiter text, field int)`|`text`|Split `string` on `delimiter` and return the given field (counting from one). When `n` is negative, returns the `|n|`-th-from-last field. |`split_part('abc~@~def~@~ghi', '~@~', 2)` → `'def'`
 `starts_with(string text, prefix text)`|`boolean`|Return true if string starts with prefix.|`starts_with('alphabet', 'alph')` → `t`
 `strpos(string, substring)`|`int`|Location of specified substring (same as `position(substring in string)`, but note the reversed argument order).|`strpos('high', 'ig')` → `2`
 `substr(string, from , count)`|`text`|Extract substring (same as `substring(string from from for count)`).|`substr('alphabet', 3, 2)` → `'ph'`