Add specs for String.replace_* functions (#4945)
Add specs for String.replace_* functions (#4945)


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