Update __iter__ docs

Author: thecjharries

docs/config.rst

@@ -17,8 +17,7 @@ The Config type
 .. method:: Config.__iter__()
 
    The :class:`Config` class has an iterator which can be used to loop
-   through all the entries in the configuration. Each element is a tuple
-   containing the name and the value of each configuration variable. Be
+   through all the entries in the configuration. Each element is a ``ConfigEntry`` object containing the name, level, and value of each configuration variable. Be
    aware that this may return multiple versions of each entry if they are
    set multiple times in the configuration files.