bpo-43162: [Enum] update docs, renable doc tests (GH-24487)

* update docs, renable doc tests
* make deprecation warning active for two releases
diff --git a/Lib/test/test_enum.py b/Lib/test/test_enum.py
index 3982d1d..69392e0 100644
--- a/Lib/test/test_enum.py
+++ b/Lib/test/test_enum.py
@@ -18,7 +18,7 @@
 
 def load_tests(loader, tests, ignore):
     tests.addTests(doctest.DocTestSuite(enum))
-    if os.path.exists('../../Doc/library/enum.rst'):
+    if os.path.exists('Doc/library/enum.rst'):
         tests.addTests(doctest.DocFileSuite(
                 '../../Doc/library/enum.rst',
                 optionflags=doctest.ELLIPSIS|doctest.NORMALIZE_WHITESPACE,
@@ -2186,7 +2186,7 @@ class Private(Enum):
         self.assertEqual(Private._Private__major_, 'Hoolihan')
 
     @unittest.skipUnless(
-            sys.version_info[:2] == (3, 10),
+            sys.version_info[:2] < (3, 12),
             'member-member access now raises an exception',
             )
     def test_warning_for_member_from_member_access(self):
@@ -2198,7 +2198,7 @@ class Di(Enum):
         self.assertIs(Di.NO, nope)
 
     @unittest.skipUnless(
-            sys.version_info[:2] > (3, 10),
+            sys.version_info[:2] >= (3, 12),
             'member-member access currently issues a warning',
             )
     def test_exception_for_member_from_member_access(self):