### _Why are the changes needed?_
- readthedocs.yml shall be readthedocs.yaml.
- Add OS version
### _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
- [ ] [Run test](https://kyuubi.readthedocs.io/en/master/develop_tools/testing.html#running-tests) locally before make a pull request
Closes#4800 from yaooqinn/readthedocs.
Closes#4800
ba70cc529 [Kent Yao] Update readthedocs.yaml
Authored-by: Kent Yao <yao@apache.org>
Signed-off-by: Kent Yao <yao@apache.org>
