Fix small community pipeline import bug and finish README (huggingface#869)

* up

* Finish

Author: patrickvonplaten

dynamic_modules_utils.py

@@ -168,7 +168,11 @@ def find_pipeline_class(loaded_module):
 
     pipeline_class = None
     for cls_name, cls in cls_members.items():
-        if cls_name != DiffusionPipeline.__name__ and issubclass(cls, DiffusionPipeline):
+        if (
+            cls_name != DiffusionPipeline.__name__
+            and issubclass(cls, DiffusionPipeline)
+            and cls.__module__.split(".")[0] != "diffusers"
+        ):
             if pipeline_class is not None:
                 raise ValueError(
                     f"Multiple classes that inherit from {DiffusionPipeline.__name__} have been found:"