fix buildVscPreviewExe.ps1 (#781)
fix buildVscPreviewExe.ps1 (#781)


DuncanmaMSFT/docfx,dotnet/docfx,DuncanmaMSFT/docfx,hellosnow/docfx,928PJY/docfx,dotnet/docfx,LordZoltan/docfx,pascalberger/docfx,928PJY/docfx,pascalberger/docfx,928PJY/docfx,superyyrrzz/docfx,LordZoltan/docfx,LordZoltan/docfx,pascalberger/docfx,dotnet/docfx,superyyrrzz/docfx,hellosnow/docfx,LordZoltan/docfx,superyyrrzz/docfx,hellosnow/docfx