Update chinese documentation for json_(un)quote function

Update chinese documentation corresponding to `json_quote` and `json_unquote` function

as per instructions  in https://github.com/apache/flink/blob/master/docs/data/sql_functions_zh.yml 

Changes are in
PR link - https://github.com/apache/flink/pull/24967 

https://github.com/apache/flink/blob/4267018323dc77773bfa1d65ee9fcb49b024e03d/docs/data/sql_functions.yml#L380

Changes would be needed in file
https://github.com/apache/flink/blob/master/docs/data/sql_functions_zh.yml 

Jira for functions - https://issues.apache.org/jira/browse/FLINK-34111