[Feature request] Timer-XL、Sundial 模型仓库

### Search before asking

- [x] I searched in the [issues](https://github.com/apache/iotdb/issues) and found nothing similar.

### Motivation

请问Timer-XL、Sundial 模型仓库分别是什么

### Solution

_No response_

### Alternatives

_No response_

### Are you willing to submit a PR?

- [ ] I'm willing to submit a PR!

The issue names the Timer-XL and Sundial model repositories but mentions no source file, test, or implementation entry point. First clarify what information is expected and where it should be documented; done would be a clear explanation of both repositories in an agreed documentation location.

Written by the indexing model from the issue text.