[it] add missing translation on index.md
[it] add missing translation on index.md

psantos10/elixir-school,ElixirVietnam/elixir-school,psantos10/elixir-school,apeacox/elixir-school,huydx/elixir-school,erickgnavar/elixir-school,doomspork/elixir-school,apeacox/elixir-school,doomspork/elixir_school,doomspork/elixir-school,psantos10/elixir-school,yuriibodarev/elixir-school,holsky/elixir-school,nscyclone/elixir-school,holsky/elixir-school,nscyclone/elixir-school,doomspork/elixir-school,ElixirVietnam/elixir-school,nscyclone/elixir-school,yuriibodarev/elixir-school,apeacox/elixir-school,erickgnavar/elixir-school,doomspork/elixir_school,doomspork/elixir_school,erickgnavar/elixir-school,huydx/elixir-school,nscyclone/elixir-school,ElixirVietnam/elixir-school,huydx/elixir-school,yuriibodarev/elixir-school,holsky/elixir-school