Improve var! docs

Author: José Valim

lib/elixir/lib/kernel/special_forms.ex

@@ -517,8 +517,11 @@ defmodule Kernel.SpecialForms do
   defmacro quote(opts, do: contents)
 
   @doc """
-  When used inside quoting, marks that the variable should not
-  be hygienezed. Check `quote/2` for more information.
+  When used inside quoting, marks that the variable should
+  not be hygienized. The argument can be either a variable
+  node (i.e. a tuple with three elements where the last
+  one is an atom) or an atom representing the variable name.
+  Check `quote/2` for more information.
   """
   defmacro var!(var)