Populate XML doc comments into OpenAPI document

This sample shows how to populate OpenAPI document with metadata from XML doc comments on methods, class, and members.

• <summary></summary> corresponds to summary in OpenAPI.
• <remark></remark> corresponds to description in OpenAPI.
• <param name="name"> corresponds to parameters[].description in OpenAPI.
• <returns><returns> corresponds to responses.200.description in OpenAPI.

We are using Scalar as the API interface.