Update function visibility to avoid noise in docs

The ex_docs had a few undocumented internal functions showing up. This
hides them.

Author: fhunleth

lib/mix/tasks/nerves/clean.ex

@@ -16,6 +16,7 @@ defmodule Mix.Tasks.Nerves.Clean do
 
   @switches [all: :boolean]
 
+  @impl Mix.Task
   def run(argv) do
     debug_info("Clean Start")
     {opts, packages, _} = OptionParser.parse(argv, switches: @switches)

lib/mix/tasks/nerves/local.ex

@@ -12,6 +12,7 @@ defmodule Mix.Tasks.Local.Nerves do
 
   This accepts the same command line options as `archive.install`.
   """
+  @impl Mix.Task
   def run(_args) do
     Mix.Task.run("archive.install", ["hex", "nerves_bootstrap", "~> 1.0"])
   end

lib/mix/tasks/nerves/new.ex

@@ -53,7 +53,7 @@ defmodule Mix.Tasks.Nerves.New do
   for {format, source, _} <- @new do
     unless format == :keep do
       @external_resource Path.join(root, source)
-      def render(unquote(source)), do: unquote(File.read!(Path.join(root, source)))
+      defp render(unquote(source)), do: unquote(File.read!(Path.join(root, source)))
     end
   end
 
@@ -152,7 +152,7 @@ defmodule Mix.Tasks.Nerves.New do
     end
   end
 
-  def run(app, mod, path, opts) do
+  defp run(app, mod, path, opts) do
     System.delete_env("MIX_TARGET")
 
     nerves_path = nerves_path(path, Keyword.get(opts, :dev, false))
@@ -219,7 +219,7 @@ defmodule Mix.Tasks.Nerves.New do
     end)
   end
 
-  def recompile(regex) do
+  defp recompile(regex) do
     if Code.ensure_loaded?(Regex) and function_exported?(Regex, :recompile!, 1) do
       apply(Regex, :recompile!, [regex])
     else