Coder plugin: Add example of customizing Workspaces Card

I know it is possible to customize the CoderWorkspacesCard to include or hide certain components. Could we provide an example of this, for example, with adding custom text below the table? I think this would be an excellent place to showcase that the "Or open in Dev Containers" can be added.

首先定位 CoderWorkspacesCard 入口点以及现有的 plugin 示例。添加一个示例，展示如何在表格下方添加文本来自定义卡片，以及如何包含“Or open in Dev Containers”；当该自定义方式已记录在可运行或易于查找的示例中时，即视为完成。

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