Which files created by Visual Studio 2017 should I ignore in version control?

https://www.gitignore.io/api/visualstudio is considerably the definitive starting point for a project in Visual Studio. Do read through it, as there are a couple sections to uncomment depending on how your project may be structured.

If you create a new project in VS2017 and add it to source control, or add an existing project to source control, VS will actually add a copy of this file to your repo as well. It seems though that the Open Folder functionality doesn't quite have that level of git integration exposed yet (there was no Add to Source Control that I could find).

Files in .vs/ directory don’t need to control versions. It’s just like VS 2015, .vs folder contains some config setting files and machine local files etc. You can refer VS uservoivce.