Add README instructions on whether to use omnisharp.useModernNet or not #3
Description
Recent VSCode plugin OmniSharp versions support the omnisharp.useModernNet setting. Maybe it's best to clarify in the README if this is required or not. I personally don't think it is, but it needs SDK style projects and can (according to the help text) result in significant performance improvements, and might be the default, but it might help to mention this anyway since users of the old package will likely be disabling this setting as it breaks the old VSCode packages' projects.