Remove references to Cldr.Currency genserver callback config (its dep…

…recated)

README.md

@@ -10,7 +10,7 @@ The package can be installed by adding `ex_cldr_currencies` to your list of depe
 ```elixir
 def deps do
   [
-    {:ex_cldr_currencies, "~> 2.5"}
+    {:ex_cldr_currencies, "~> 2.13"}
   ]
 end
 ```
@@ -19,7 +19,7 @@ end
 
 [ISO4217](https://en.wikipedia.org/wiki/ISO_4217) permits the creation of private use currencies. These are denoted by currencies that start with "X" followed by two characters.  New currencies can be created with `Cldr.Currency.new/2` however in order to do so a supervisor must be started which maintains an `:ets` table that holds the custom currencies.
 
-Since the currencies are stored in an `:ets` table they are transient and will be lost on application restart. It is the developers responsibility to define the required private use currencies on application restart. One option is to use a callback function as described below.
+Since the currencies are stored in an `:ets` table they are transient and will be lost on application restart. It is the developers responsibility to define the required private use currencies on application restart.
 
 ### Starting the private use currency supervisor
 
@@ -43,51 +43,12 @@ defmodule MyApp do
 
     opts = [strategy: :one_for_one, name: MoneyTest.Supervisor]
     Supervisor.start_link(children, opts)
+
+    # Load your custom currencies now that the
+    # Cldr.Currency genserver is running
+    # load_my_custom_currencies()
   end
 end
 ```
 
-### Loading private use currencies at application start
-If private use currencies are required then defining them when the application starts can be accomplished by providing a callback to the `Cldr.Currency` supervisor as either a `{Module, :function, args}` tuple or as an anonymous function that takes two arguments. 
 
-The callback will be called when the custom currency supervisor is starting. The callback function is expected (but not required) to call `Cldr.Currency.new/2` to load custom currencies. Most typically this would be done to load currency definitions from a database (or other serialization) and call `Cldr.Currency.new/2` for each custom currency. In that way, any application code that depends upon the availability of custom currencies can be assured that they are available since the callback will be invoked before the application code starts.
-
-If the callback returns `:error` or `{:error, String.t()}` then the custom currency superisor is shutdown and error is returned.
-
-Here are some examples:
-```elixir
-# Using an anonymous function
-defmodule MyApp.Application do
-  use Application
-
-  def start(_type, _args) do
-    # Start the service which maintains the
-    # :ets table that holds the private use currencies
-    children = [
-      {Cldr.Currency, [callback: fn pid, table ->
-        "#{inspect pid}: Starting private use currency store for #{inspect table}" end]}
-    ]
-
-    opts = [strategy: :one_for_one, name: MyApp.Supervisor]
-    Supervisor.start_link(children, opts)
-  end
-end
-
-# Using an MFA
-defmodule MyApp.Application do
-  use Application
-
-  def start(_type, _args) do
-    # In this example, the `pid` and `table` will be
-    # prepended to the `args`. In this example therefore
-    # the callback will be `MyAppModule.my_function(pid, table)`
-    children = [
-      {Cldr.Currency, [callback: {MyAppModule, :my_function, []}]}
-    ]
-
-    opts = [strategy: :one_for_one, name: MyApp.Supervisor]
-    Supervisor.start_link(children, opts)
-  end
-end
-
-```

lib/cldr/eternal/supervisor.ex

@@ -17,11 +17,11 @@ defmodule Cldr.Eternal.Supervisor do
   alias Cldr.Eternal.Table
 
   @doc """
-  Starts an Eternal Supervision tree which manages the two internal servers.
-  
-  This returns a Tuple containing the table name, so it cannot be used inside a
-  Supervision tree directly. If you want to use this Supervisor, you should go
-  via the main Eternal module.
+  Starts an Eternal Supervision tree which manages the two internal servers.
+
+  This returns a Tuple containing the table name, so it cannot be used inside a
+  Supervision tree directly. If you want to use this Supervisor, you should go
+  via the main Cldr.Eternal module.
   """
   # @spec start_link(name :: atom, ets_opts :: Keyword.t, opts :: Keyword.t) ::
   #       { :ok, pid, Table.t } | :ignore |