docs(openapi): add docs for attachment

[GMishx]

Please provide a summary of your changes here.

Added OpenAPI docs using springdoc for:

• /attachments
• /changelog
• /clearingrequest

It is continuation of #2071

Suggest Reviewer

@KoukiHama
@heliocastro

How To Test?

• The Swagger UI for the API should be available at http://localhost:8080/resource/api/swagger-ui/index.html
  • Read the documentation for the endpoints.
• OpenAPI JSON file should be available at http://localhost:8080/resource/api-docs

[heliocastro]

Hey @GMishx , after compiled the pr, still got this:

[GMishx]

@heliocastro try adding the index.html

http://localhost:8080/resource/api/swagger-ui/index.html

[heliocastro]

Tested and all ok.
Great opportunity to us get hid of the old .adoc documentation and use swagger only.