Fix pipeline_flux_controlnet.py (#11095)

* Fix pipeline_flux_controlnet.py

* Fix style

Author: co63oc

src/diffusers/pipelines/flux/pipeline_flux_controlnet.py

@@ -63,6 +63,7 @@
         >>> from diffusers import FluxControlNetPipeline
         >>> from diffusers import FluxControlNetModel
 
+        >>> base_model = "black-forest-labs/FLUX.1-dev"
         >>> controlnet_model = "InstantX/FLUX.1-dev-controlnet-canny"
         >>> controlnet = FluxControlNetModel.from_pretrained(controlnet_model, torch_dtype=torch.bfloat16)
         >>> pipe = FluxControlNetPipeline.from_pretrained(