docstrings_on_attributes: true removes examples

Describe the bug
If I add docstrings_on_attributes: true to my config, then example fields in my openapi schemaare removed entirely from the docstrings.

The default behavior seems to be to list first the description and then the example field in the attribute docstring at the top of the class. I'd expect that behavior to be retained when I add docstrings_on_attributes: true

OpenAPI Spec File
A link to an OpenAPI document which produces this issue. Ideally, write a minimal reproduction only containing the problematic pieces.

Desktop (please complete the following information):

• OS: [e.g. macOS 10.15.1] macOS 15.5
• Python Version: [e.g. 3.8.0] 3.11.9
• openapi-python-client version [e.g. 0.1.0] 0.25.1

Additional context
Add any other context about the problem here.

该 issue 提到了 openapi-python-client 0.25.1 和 docstrings_on_attributes 配置，但没有指定源文件或测试。首先，使用最小的 OpenAPI 文档，在启用和不启用该选项的情况下复现生成的 docstring。完成标准是：启用该选项时，属性 docstring 保留 description 和 example 两个字段。