Update SDK requirement in windows-instructions

Commit migrated from https://github.com/dotnet/corefx/commit/e2ecd2c33aed216f9a1062044aedf10e25ee8ca4

diff --git a/docs/libraries/building/windows-instructions.md b/docs/libraries/building/windows-instructions.md
index c367bed..d777add 100644 (file)
--- a/docs/libraries/building/windows-instructions.md
+++ b/docs/libraries/building/windows-instructions.md
@@ -4,7 +4,7 @@ Building CoreFX on Windows
 ## Required Software
 
 1. **[Visual Studio 2017](https://www.visualstudio.com/downloads/)** or **[Visual Studio 2019](https://visualstudio.microsoft.com/vs/preview/)** (Community, Professional, Enterprise) with the latest update must be installed. The Community version is completely free.
-2. **[.NET Core SDK](https://www.microsoft.com/net/download/windows)** >= v2.1.401 must be installed which will add the `dotnet` toolchain to your path.
+2. **[.NET Core SDK](https://www.microsoft.com/net/download/windows)** >= v3.0.0-preview3 must be installed which will add the `dotnet` toolchain to your path.
 3. **[CMake](https://cmake.org/)** must be installed from [the CMake download page](https://cmake.org/download/#latest) and added to your path. CMake 3.14 or later is required to build with VS 2019.
 
 ### Visual Studio 2019