No proper API reference is generated for SageMaker SDK v3

**What did you find confusing? Please describe.**
The customer tried to understand the structure of sagemaker.ai_registry.dataset.DataSet and clarify how to configure max context length for datasets used in RLAIF. They failed to do it as no proper API Reference is provided.

**Describe how documentation can be improved**
Please provide proper API Reference asap, otherwise people are lost in the tutorials and have no idea about fine-tuned and advanced system capabilities and configurations. It can be generated automatically from the code.
Example: https://scikit-learn.org/stable/api/index.html.

**Additional context**
Search is not working: Searching for "sagemaker.ai_registry.dataset.DataSet" did not bring any information about the DataSet constructor method and parameters.

首先定位 sagemaker.ai_registry.dataset.DataSet 的实现，以及 SDK 中现有的文档生成入口。将预期的 API 参考与 scikit-learn API 参考示例进行比较，然后验证通过文档搜索可以发现 DataSet 构造函数及其参数，包括最大上下文长度配置。

由索引模型根据 Issue 内容生成。