Update documentation / module description

Hi, thanks for this great module!

I see on the module description page it says:

HOW CAN I ACCESS MY SETTINGS?

If this config page is used to store settings then you should use config_pages_get() or config_pages_config() functions.
If this config page is singleton page like custom homepage, you can use config_pages_render(), config_pages_render_field() to use in your code, or CTools Content Type called "Config Pages: Content" to place on panels.

However, of these functions I can only use config_pages_config(), the others are undefined. I can work by it, but seems the these might be deprecated and the description doesn't reflect that?