MERGE: Closes #20872: dbm/gdbm/ndbm close methods are not documented

diff --cc Doc/library/dbm.rst
index b0133d840594cd92f164db3efd0cb3823c07db2c,e6a82d67ce57c51eb5b58d957961947e59ebb039..3f3c43d4383fba51737b821ee41537c199b7c793
--- 1/Doc/library/dbm.rst
--- 2/Doc/library/dbm.rst
+++ b/Doc/library/dbm.rst
@@@ -324,13 -332,9 +333,13 @@@ The module defines the following
     database has to be created.  It defaults to octal ``0o666`` (and will be modified
     by the prevailing umask).
  
 +   .. versionchanged:: 3.5
 +      :func:`.open` always creates a new database when the flag has the value
 +      ``'n'``.
 +
     In addition to the methods provided by the
     :class:`collections.abc.MutableMapping` class, :class:`dumbdbm` objects
-    provide the following method:
+    provide the following methods:
  
     .. method:: dumbdbm.sync()