Fix example usage of BaseFormatter.for_type_by_name.

I propose a small documentation fix for this excellent feature of
IPython.

The current example doesn't work because the type module and type name
are lumped into one string. They must be given as separate strings.

See docstring:

```
Signature: BaseFormatter.for_type_by_name(self, type_module, type_name, func=None)
```

For extra clarity, I have added a submodule to this made-up example
module so that the pattern is clear.

docs/source/config/integrating.rst

@@ -1,110 +1,110 b''
 .. _integrating:
 
 =====================================
 Integrating your objects with IPython
 =====================================
 
 Tab completion
 ==============
 
 To change the attributes displayed by tab-completing your object, define a
 ``__dir__(self)`` method for it. For more details, see the documentation of the
 built-in `dir() function <http://docs.python.org/library/functions.html#dir>`_.
 
 You can also customise key completions for your objects, e.g. pressing tab after
 ``obj["a``. To do so, define a method ``_ipython_key_completions_()``, which
 returns a list of objects which are possible keys in a subscript expression
 ``obj[key]``.
 
 .. versionadded:: 5.0
    Custom key completions
 
 .. _integrating_rich_display:
 
 Rich display
 ============
 
 The notebook and the Qt console can display richer representations of objects.
 To use this, you can define any of a number of ``_repr_*_()`` methods. Note that
 these are surrounded by single, not double underscores.
 
 Both the notebook and the Qt console can display ``svg``, ``png`` and ``jpeg``
 representations. The notebook can also display ``html``, ``javascript``,
 ``markdown`` and ``latex``. If the methods don't exist, or return ``None``, it
 falls back to a standard ``repr()``.
 
 For example::
 
     class Shout(object):
         def __init__(self, text):
             self.text = text
         
         def _repr_html_(self):
             return "<h1>" + self.text + "</h1>"
 
 We often want to provide frontends with guidance on how to display the data. To
 support this, ``_repr_*_()`` methods can also return a ``(data, metadata)``
 tuple where ``metadata`` is a dictionary containing arbitrary key-value pairs for
 the frontend to interpret. An example use case is ``_repr_jpeg_()``, which can
 be set to return a jpeg image and a ``{'height': 400, 'width': 600}`` dictionary
 to inform the frontend how to size the image.
 
 There are also two more powerful display methods:
 
 .. class:: MyObject
 
    .. method:: _repr_mimebundle_(include=None, exclude=None)
 
      Should return a dictionary of multiple formats, keyed by mimetype, or a tuple
      of two dictionaries: *data, metadata*. If this returns something, other
      ``_repr_*_`` methods are ignored. The method should take keyword arguments
      ``include`` and ``exclude``, though it is not required to respect them.
 
    .. method:: _ipython_display_()
 
       Displays the object as a side effect; the return value is ignored. If this
       is defined, all other display methods are ignored.
 
 To customize how the REPL pretty-prints your object, add a `_repr_pretty_`
 method to the class.  The method should accept a pretty printer, and a boolean
 that indicates whether the printer detected a cycle.  The method should act on
 the printer to produce your customized pretty output.  Here is an example::
 
     class MyObject(object):
 
         def _repr_pretty_(self, p, cycle):
             if cycle:
                 p.text('MyObject(...)')
             else:
                 p.text('MyObject[...]')
 
 For details, see :py:mod:`IPython.lib.pretty`.
 
 Formatters for third-party types
 --------------------------------
 
 The user can also register formatters for types without modifying the class::
 
-    from bar import Foo
+    from bar.baz import Foo
 
     def foo_html(obj):
         return '<marquee>Foo object %s</marquee>' % obj.name
 
     html_formatter = get_ipython().display_formatter.formatters['text/html']
     html_formatter.for_type(Foo, foo_html)
 
     # Or register a type without importing it - this does the same as above:
-    html_formatter.for_type_by_name('bar.Foo', foo_html)
+    html_formatter.for_type_by_name('bar.baz', 'Foo', foo_html)
 
 Custom exception tracebacks
 ===========================
 
 Rarely, you might want to display a custom traceback when reporting an
 exception. To do this, define the custom traceback using
 `_render_traceback_(self)` method which returns a list of strings, one string
 for each line of the traceback. For example, the `ipyparallel
 <http://ipyparallel.readthedocs.io/>`__ a parallel computing framework for
 IPython, does this to display errors from multiple engines.
 
 Please be conservative in using this feature; by replacing the default traceback
 you may hide important information from the user.