Add Enum.filter/2 lesson (#1342) (#1349)
Add Enum.filter/2 lesson (#1342) (#1349)

* Add filter/2 lesson (#1342)

* Fix explanation of filter/2 lesson

* Bump basics enum version

doomspork/elixir_school,psantos10/elixir-school,psantos10/elixir-school,doomspork/elixir_school,doomspork/elixir_school,doomspork/elixir-school,nscyclone/elixir-school,nscyclone/elixir-school,nscyclone/elixir-school,nscyclone/elixir-school,psantos10/elixir-school,doomspork/elixir-school,doomspork/elixir-school