Elixir: Fix Enum example and rename "char list" to "charlist"

The charlist change is needed because all Elixir core is using the
"charlist" version. We also should use to keep consistency.

Also, to_char_list/1 is deprecated since Elixir 1.5.

elixir.md

@@ -59,7 +59,7 @@ users = [ "Tom", "Dick", "Harry" ]
 {: data-line="1"}
 
 ```elixir
-Enum.map(user, fn user ->
+Enum.map(users, fn user ->
   IO.puts "Hello " <> user
 end)
 ```
@@ -155,7 +155,7 @@ end
 | `23`                    | Integer         |
 | `3.14`                  | Float           |
 | ---                     | ---             |
-| `'hello'`               | Char list       |
+| `'hello'`               | Charlist        |
 | `<<2, 3>>`              | Binary          |
 | `"hello"`               | Binary string   |
 | `:hello`                | Atom            |
@@ -308,7 +308,7 @@ n = 12
 
 ```elixir
 n |> digits()         # → [1, 2]
-n |> to_char_list()   # → '12'
+n |> to_charlist()    # → '12'
 n |> to_string()      # → "12"
 n |> is_even()
 n |> is_odd()
@@ -317,7 +317,7 @@ n |> is_odd()
 ```elixir
 # Different base:
 n |> digits(2)        # → [1, 1, 0, 0]
-n |> to_char_list(2)  # → '1100'
+n |> to_charlist(2)   # → '1100'
 n |> to_string(2)     # → "1100"
 ```
 
@@ -676,7 +676,7 @@ exp = ~r/hello/i
 ~w(list of strings)
 ~s[strings with #{interpolation} and \x20 escape codes]
 ~S[no interpolation and no escapes]
-~c(char list)
+~c(charlist)
 ```
 
 Allowed chars: `/` `|` `"` `'` `(` `[` `{` `<` `"""`.