Add docs

issues/lib/issues/cli.ex

@@ -10,6 +10,13 @@ defmodule Issues.CLI do
     parse_args(argv)
   end
 
+  @doc """
+  `argv` can be -h or --help, which returns :help.
+  Otherwise it is a github user name, project name, and (optionally)
+  the number of entries to format.
+
+  Return a tuple of `{ user, project, count }`, or `:help` if help was given
+  """
   def parse_args(argv) do
     parse =
       OptionParser.parse(argv,