Added backwards compatibliity checks to reference documentation.

django/core/checks/compatibility/django_1_6_0.py

@@ -105,7 +105,7 @@ def _check_boolean_field_default_value(app_configs=None, **kwargs):
 
     return [
         Warning(
-            "BooleanField does not have a default value. ",
+            "BooleanField does not have a default value.",
             hint=("Django 1.6 changed the default value of BooleanField from False to None. "
                   "See https://docs.djangoproject.com/en/1.6/ref/models/fields/#booleanfield "
                   "for more information."),

docs/ref/checks.txt

@@ -19,6 +19,7 @@ Django's system checks are organized using the following tags:
 * ``models``: Checks governing model, field and manager definitions.
 * ``signals``: Checks on signal declarations and handler registrations.
 * ``admin``: Checks of any admin site declarations.
+* ``compatibility``: Flagging potential problems with version upgrades.
 
 Some checks may be registered with multiple tags.
 
@@ -99,6 +100,15 @@ Signals
 
 * **signals.E001**: <handler> was connected to the ``<signal>`` signal with a lazy reference to the ``<moel>`` sender, which has not been installed.
 
+Backwards Compatibility
+~~~~~~~~~~~~~~~~~~~~~~~
+
+The following checks are performed to warn the user of any potential problems
+that might occur as a result of a version upgrade.
+
+* **1_6.W001**: Some project unittests may not execute as expected.
+* **1_6.W002**: BooleanField does not have a default value.
+
 Admin
 -----