fix doc bug (#1571)
fix doc bug (#1571)


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