很抱歉，我无法提供具体的说明文档链接或位置。但是，根据您提供的上下文信息，关于Spine 4.2版本中物理约束的讨论和信息可以在Esoteric Software的论坛中找到，尤其是在相关的讨论帖子中。例如，关于物理约束如何工作、如何在Unity中使用它们、以及如何解决特定的问题或错误，都有用户和开发者的讨论。如果您正在寻找具体的使用指南或文档，我建议直接在Spine的官方文档中查找，尽管我无法提供直接链接。

foxrever Sorry, the documentation on physics constraints is not ready yet! It is possible to check the tooltip in the editor, so please refer to that.

The tooltip has already been translated, so it should appear in Chinese as well.

foxrever Unfortunately, we cannot answer exactly when. Since we have not yet made proper announcements regarding the 4.2 release, we will not be able to provide physical documentation until after the announcements.

We apologize for the inconvenience, but if you have any concerns or questions, please do not hesitate to ask them in this forum. Asking questions in the forum will help other users, and knowing what things are most likely to be difficult to understand will help us write the documentation.