Add default `html[lang]` to appendix pages
Add default `html[lang]` to appendix pages

nscyclone/elixir-school,doomspork/elixir-school,nscyclone/elixir-school,doomspork/elixir_school,doomspork/elixir-school,doomspork/elixir-school,doomspork/elixir_school,nscyclone/elixir-school,nscyclone/elixir-school,doomspork/elixir_school