Update reference to Keyword.delete/3 (#9394)
Update reference to Keyword.delete/3 (#9394)

ExDoc is giving a warning since it has been deprecated and @doc is set to false.
> warning: documentation references Keyword.delete/3 but it doesn't exist or it's listed as @doc false (parsing Keyword docs)

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