Remove left over python style config remnant, doc update.

Replace three with two as there are only two items in the list.
Remove setting that was used in the code for python style init files.
Support for python style init files removed a while ago and were
deprecated in 0.8 timeframe IIRC.

Author: rouilj

roundup/configuration.py

@@ -1772,17 +1772,14 @@ class CoreConfig(Config):
     """Roundup instance configuration.
 
     Core config has a predefined layout (see the SETTINGS structure),
-    supports loading of old-style pythonic configurations and holds
-    three additional attributes:
+    two additional attributes:
         detectors:
             user-defined configuration for detectors
         ext:
             user-defined configuration for extensions
 
     """
 
-    # module name for old style configuration
-    PYCONFIG = "config"
     # user configs
     ext = None
     detectors = None