Fix grammar in the Integer.undigits/2 docs (#8224)
Fix grammar in the Integer.undigits/2 docs (#8224)

[ci skip]
lexmag/elixir,lexmag/elixir,joshprice/elixir,ggcampinho/elixir,pedrosnk/elixir,kelvinst/elixir,elixir-lang/elixir,michalmuskala/elixir,kimshrier/elixir,ggcampinho/elixir,kimshrier/elixir,pedrosnk/elixir,kelvinst/elixir