Update conf.py

docs/source/conf.py

@@ -23,7 +23,7 @@ class Mock(MagicMock):
 
 # Mock tango modules
 MOCK_MODULES = ['PyTango', 'tango', 'tango.server', 'run', 'DeviceMeta', 'command',
-                'future', 'future.utils', 'logging']
+                'future', 'future.utils', 'logging', 'logging.handlers']
 sys.modules.update((mod_name, Mock()) for mod_name in MOCK_MODULES)
 
 # If extensions (or modules to document with autodoc) are in another directory,