[3.1.x] Refs #24763 -- Moved DoesNotExist to Model class docs.

Backport of b5f0efa19c from master

docs/ref/models/class.txt

@@ -11,6 +11,20 @@ reference guides </ref/models/index>`.
 Attributes
 ==========
 
+``DoesNotExist``
+----------------
+
+.. exception:: Model.DoesNotExist
+
+    This exception is raised by the ORM when an expected object is not found.
+    For example, :meth:`.QuerySet.get` will raise it when no object is found
+    for the given lookups.
+
+    Django provides a ``DoesNotExist`` exception as an attribute of each model
+    class to identify the class of object that could not be found, allowing you
+    to catch exceptions for a particular model class. The exception is a
+    subclass of :exc:`django.core.exceptions.ObjectDoesNotExist`.
+
 ``objects``
 -----------
 

docs/ref/models/instances.txt

@@ -846,20 +846,6 @@ duplicated. That also means you cannot use those methods on unsaved objects.
 Other attributes
 ================
 
-``DoesNotExist``
-----------------
-
-.. exception:: Model.DoesNotExist
-
-    This exception is raised by the ORM in a couple places, for example by
-    :meth:`QuerySet.get() <django.db.models.query.QuerySet.get>` when an object
-    is not found for the given query parameters.
-
-    Django provides a ``DoesNotExist`` exception as an attribute of each model
-    class to identify the class of object that could not be found and to allow
-    you to catch a particular model class with ``try/except``. The exception is
-    a subclass of :exc:`django.core.exceptions.ObjectDoesNotExist`.
-
 ``_state``
 ----------