### _Why are the changes needed?_
- add doc for`POST /admin/refresh/user_defaults_conf` REST Api , which introduced in #3982
### _How was this patch tested?_
- [x] 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#4077 from bowenliang123/3982-followup.
Closes#3982
a6acb389 [liangbowen] add REST api doc of `POST /admin/refresh/user_defaults_conf`
Authored-by: liangbowen <liangbowen@gf.com.cn>
Signed-off-by: ulysses-you <ulyssesyou@apache.org>
2563e3c3ad