Fix additional typos in docs (thanks tomthorogood)

docs/config.rst

@@ -365,7 +365,7 @@ values. The valid configuration keys are listed below.
 
     Then you don't need to specify a ``world`` key in the render dictionaries::
 
-        render['arender'] = {
+        renders['arender'] = {
                 'title': 'This render doesn't explicitly declare a world!',
                 }