doc: fix commenter_options type

Author: joaothallis

instrumentation/opentelemetry-instrumentation-sqlalchemy/src/opentelemetry/instrumentation/sqlalchemy/__init__.py

@@ -136,7 +136,7 @@ def _instrument(self, **kwargs):
                 ``tracer_provider``: a TracerProvider, defaults to global
                 ``meter_provider``: a MeterProvider, defaults to global
                 ``enable_commenter``: bool to enable sqlcommenter, defaults to False
-                ``commenter_options``: dict of sqlcommenter config, defaults to None
+                ``commenter_options``: dict of sqlcommenter config, defaults to {}
 
         Returns:
             An instrumented engine if passed in as an argument or list of instrumented engines, None otherwise.