Removed versionadded/changed annotations for 3.1.

docs/howto/custom-management-commands.txt

@@ -364,7 +364,3 @@ the management command to exit with, using :func:`sys.exit`.
 If a management command is called from code through
 :func:`~django.core.management.call_command`, it's up to you to catch the
 exception when needed.
-
-.. versionchanged:: 3.1
-
-    The ``returncode`` argument was added.

docs/howto/error-reporting.txt

@@ -269,16 +269,12 @@ following attributes and methods:
 
     .. attribute:: cleansed_substitute
 
-        .. versionadded:: 3.1
-
         The string value to replace sensitive value with. By default it
         replaces the values of sensitive variables with stars
         (``**********``).
 
     .. attribute:: hidden_settings
 
-        .. versionadded:: 3.1
-
         A compiled regular expression object used to match settings and
         ``request.META`` values considered as sensitive. By default equivalent
         to::
@@ -307,8 +303,6 @@ following attributes and methods:
         traceback frame. Sensitive values are replaced with
         :attr:`cleansed_substitute`.
 
-.. versionadded:: 3.1
-
 If you need to customize error reports beyond filtering you may specify a
 custom error reporter class by defining the
 :setting:`DEFAULT_EXCEPTION_REPORTER` setting::