### _Why are the changes needed?_
Add a hint in creating batch REST API.
### _How was this patch tested?_
- [ ] Add some test cases that check the changes thoroughly including negative and positive cases if possible
- [ ] Add screenshots for manual tests if appropriate
- [x] [Run test](https://kyuubi.apache.org/docs/latest/develop_tools/testing.html#running-tests) locally before make a pull request
Closes#3622 from deadwind4/create-batch-rest-doc.
Closes#3621
0d1e6764 [Luning Wang] [KYUUBI #3621][DOCS] Add a hint in create batch REST api
Authored-by: Luning Wang <wang4luning@gmail.com>
Signed-off-by: Cheng Pan <chengpan@apache.org>