update release note.
update release note.

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