Remove unused folder in All.sln
Remove unused folder in All.sln

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