Also merge ItemViewModel's property for tocMetadata option (#1271)
Also merge ItemViewModel's property for tocMetadata option (#1271)


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