docs: enable inherited members display by default

Added :inherited-members: to autodoc_default_options in conf.py
so all classes automatically show inherited methods and attributes
from their base classes. This makes Connect5 show members from
GatewayMixin and ModularBaseConnect_4_5, for example.

docs/conf.py

@@ -34,6 +34,7 @@ autodoc_default_options = {
     'member-order': 'bysource',
     'special-members': '__init__',
     'undoc-members': True,
+    'inherited-members': True,
     'exclude-members': '__weakref__'
 }