Fixed #21951 -- Updated docs to use __str__ for Python 3

Thanks Tim Graham for the report and recommendations

docs/ref/contrib/gis/commands.txt

@@ -65,7 +65,7 @@ of using ``ogrinspect`` :ref:`in the tutorial <ogrinspect-intro>`.
 
 .. django-admin-option:: --name-field <name_field>
 
-   Generates a ``__unicode__`` routine (``__str__`` on Python 3) on the model
+   Generates a ``__str__`` routine (``__unicode__`` on Python 2) on the model
    that will return the given field name.
 
 .. django-admin-option:: --no-imports

docs/ref/contrib/gis/layermapping.txt

@@ -61,8 +61,7 @@ Example
         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):
+        def __str__(self):              # __unicode__ on Python 2
             return 'Name: %s' % self.name
 
 3. Use :class:`LayerMapping` to extract all the features and place them in the

docs/ref/contrib/gis/tutorial.txt

@@ -244,8 +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):
+        def __str__(self):              # __unicode__ on Python 2
             return self.name
 
 Please note two important things: