Reword deprecation warning.

IPython/core/oinspect.py

@@ -695,7 +695,8 b' class Inspector(Colorable):'
         """DEPRECATED. Compute a dict with detailed information about an object.
         """
         if formatter is not None:
-            warnings.warn('Inspector.info(formatter) keyword is deprecated as of IPython 5.0 and will have no effects.',
+            warnings.warn('The `formatter` keyword argument to `Inspector.info`'
+                     'is deprecated as of IPython 5.0 and will have no effects.',
                       DeprecationWarning, stacklevel=2)
         return self._info(obj, oname=oname, info=info, detail_level=detail_level)