Document similar projects and write about the differences with this project

[jkone27]

• https://github.com/richardszalay/mockhttp (similar project)
• https://github.com/WireMock-Net/WireMock.Net?tab=readme-ov-file (different as it runs a true http mock server)
  others?
• https://github.com/markvincze/Stubbery (also true "test" http server)