[es] Update collections.md (#2429)
[es] Update collections.md (#2429)

* Update collections.md

Correcciones de palabras incompletas y gramaticales (tildes).
doomspork/elixir_school,doomspork/elixir_school,doomspork/elixir-school,doomspork/elixir-school,doomspork/elixir-school,doomspork/elixir_school