I was working on .NET Core Version 1.1 with Visual Studio 2017. After the release of .NET Core 2.0, I wanted to make this version available in my VS2017.
The simplest way to achieve this is to upgrade Visual Studio from version 15.0 to 15.3 or later by downloading it from the updates section.
After the update is complete, download SDK and install from
.NET Downloads
That's all. You will be able to target your new applications to .NET core 2.0.