Make Version.Requirement public (#8920)
Make Version.Requirement public (#8920)

The `Version.Requirement` struct is mentioned in several places
of the `Version` documentation, used as an argument of
`Version.compile_requirement/1` and `Version.match?/3`, and
returned as a result of `Version.parse_requirement/1` and
`Version.parse_requirement!/1`.

ggcampinho/elixir,ggcampinho/elixir,pedrosnk/elixir,elixir-lang/elixir,pedrosnk/elixir,kimshrier/elixir,lexmag/elixir,kelvinst/elixir,joshprice/elixir,lexmag/elixir,kimshrier/elixir,kelvinst/elixir,michalmuskala/elixir