Update docs/en/sql-reference/functions/type-conversion-functions.md

Co-authored-by: Nolgarev <56617294+olgarev@users.noreply.github.com>

docs/en/sql-reference/functions/type-conversion-functions.md

@@ -702,7 +702,7 @@ parseDateTimeBestEffortUSOrNull(time_string [, time_zone]);
 **Parameters**
 
 -   `time_string` — String containing a date or date with time to convert. The date must be in the US date format (`MM/DD/YYYY`). [String](../../sql-reference/data-types/string.md).
--   `time_zone` — Time zone. The function parses `time_string` according to the time zone. [String](../../sql-reference/data-types/string.md).
+-   `time_zone` — [Timezone](../../operations/server-configuration-parameters/settings.md#server_configuration_parameters-timezone). The function parses `time_string` according to the timezone. Optional. [String](../../sql-reference/data-types/string.md).
 
 **Supported non-standard formats**