[JP] Update `Enum.chunk_by/2` in enum lesson (#549)
[JP] Update `Enum.chunk_by/2` in enum lesson (#549)

* Apply #528 and #537 changes to Japanese translation
yuriibodarev/elixir-school,doomspork/elixir_school,huydx/elixir-school,doomspork/elixir-school,holsky/elixir-school,ElixirVietnam/elixir-school,psantos10/elixir-school,huydx/elixir-school,nscyclone/elixir-school,doomspork/elixir-school,erickgnavar/elixir-school,ElixirVietnam/elixir-school,huydx/elixir-school,yuriibodarev/elixir-school,nscyclone/elixir-school,erickgnavar/elixir-school,psantos10/elixir-school,doomspork/elixir_school,nscyclone/elixir-school,nscyclone/elixir-school,doomspork/elixir_school,yuriibodarev/elixir-school,ElixirVietnam/elixir-school,psantos10/elixir-school,doomspork/elixir-school,erickgnavar/elixir-school,holsky/elixir-school,holsky/elixir-school