crop_params: link the pipeline step

crop_params/README.md

@@ -1,7 +1,7 @@
 # Crop parameters
 
 One square crop box per clip that frames the signer, found by running a YOLO person detector on every frame
-(code: [crop-params](https://github.com/crocosign/crop-params)). The videos are stored uncropped; the crop is
+(code: [pjm-data, step 05](https://github.com/crocosign/pjm-data/tree/main/dataset-processing/05_crop_params)). The videos are stored uncropped; the crop is
 applied when loading data.
 
 - `crop_params.lmdb/`: LMDB with the clip key (the `__key__` of the segment record) as key and a msgpack map as