Remove unreachable line (elixir-lang#850)

Author: gusaaaaa

getting-started/mix-otp/task-and-gen-tcp.markdown

@@ -43,7 +43,6 @@ end
 defp loop_acceptor(socket) do
   {:ok, client} = :gen_tcp.accept(socket)
   serve(client)
-  loop_acceptor(socket)
 end
 
 defp serve(socket) do