Fixed #20224 -- Update docs examples which mention __unicode__

Thanks Marc Tamlyn and Tim Graham for the review.

docs/ref/contrib/admin/actions.txt

@@ -57,6 +57,7 @@ simple news application with an ``Article`` model::
         body = models.TextField()
         status = models.CharField(max_length=1, choices=STATUS_CHOICES)
 
+        # On Python 3: def __str__(self):
         def __unicode__(self):
             return self.title
 

docs/ref/contrib/admin/index.txt

@@ -438,7 +438,8 @@ subclass::
         list_display = ('first_name', 'last_name')
 
     If you don't set ``list_display``, the admin site will display a single
-    column that displays the ``__unicode__()`` representation of each object.
+    column that displays the ``__unicode__()`` (``__str__()`` on Python 3)
+    representation of each object.
 
     You have four possible values that can be used in ``list_display``:
 
@@ -488,7 +489,7 @@ subclass::
     A few special cases to note about ``list_display``:
 
     * If the field is a ``ForeignKey``, Django will display the
-      ``__unicode__()`` of the related object.
+      ``__unicode__()`` (``__str__()`` on Python 3) of the related object.
 
     * ``ManyToManyField`` fields aren't supported, because that would
       entail executing a separate SQL statement for each row in the table.

docs/ref/contrib/contenttypes.txt

@@ -270,6 +270,7 @@ A simple example is a tagging system, which might look like this::
         object_id = models.PositiveIntegerField()
         content_object = generic.GenericForeignKey('content_type', 'object_id')
 
+        # On Python 3: def __str__(self):
         def __unicode__(self):
             return self.tag
 

docs/ref/contrib/gis/commands.txt

@@ -65,8 +65,8 @@ of using ``ogrinspect`` :ref:`in the tutorial <ogrinspect-intro>`.
 
 .. django-admin-option:: --name-field <name_field>
 
-   Generates a ``__unicode__`` routine on the model that will return the
-   the given field name.
+   Generates a ``__unicode__`` routine (``__str__`` on Python 3) on the model
+   that will return the the given field name.
 
 .. django-admin-option:: --no-imports
 

docs/ref/contrib/gis/layermapping.txt

@@ -60,6 +60,8 @@ Example
         name = models.CharField(max_length=25) # corresponds to the 'str' field
         poly = models.PolygonField(srid=4269) # we want our model in a different SRID
         objects = models.GeoManager()
+
+        # On Python 3: def __str__(self):
         def __unicode__(self):
             return 'Name: %s' % self.name
 

docs/ref/contrib/gis/tutorial.txt

@@ -244,6 +244,7 @@ model to represent this data::
         objects = models.GeoManager()
 
         # Returns the string representation of the model.
+        # On Python 3: def __str__(self):
         def __unicode__(self):
             return self.name