Slightly improve Macro.generate_arguments/2 (#8842)
Slightly improve Macro.generate_arguments/2 (#8842)

I added a bodyless clause so that arguments are clearly named in the 
documentation. I also added a is_atom/1 guard to the first function 
clause so that we consistently check that the context is an atom.
michalmuskala/elixir,kimshrier/elixir,kelvinst/elixir,pedrosnk/elixir,pedrosnk/elixir,lexmag/elixir,ggcampinho/elixir,kimshrier/elixir,elixir-lang/elixir,joshprice/elixir,lexmag/elixir,ggcampinho/elixir,kelvinst/elixir