[Bug] 文档中 key doris.read.field 不正确

### Search before asking

- [x] I had searched in the [issues](https://github.com/apache/incubator-doris/issues?q=is%3Aissue) and found no similar issues.

### Version

25.1.0

### What's Wrong?

代码中有 s, 文档中没有 s。

public static final ConfigOption DORIS_READ_FIELDS = ConfigOptions.name("doris.read.fields").stringType().withoutDefaultValue().withDescription("");

### What You Expected?

-

### How to Reproduce?

_No response_

### Anything Else?

_No response_

### Are you willing to submit PR?

- [ ] Yes I am willing to submit a PR!

### Code of Conduct

- [x] I agree to follow this project's [Code of Conduct](https://www.apache.org/foundation/policies/conduct)

Search the documentation for the key `doris.read.field` and compare it with the Java declaration `DORIS_READ_FIELDS`, which uses `doris.read.fields`. Update the documented key to match the declaration, then verify that no remaining documentation references use the singular form.

Written by the indexing model from the issue text.