[Enhance]: Add cfg link in README.md (#4190)

configs/albu_example/README.md

configs/atss/README.md

configs/carafe/README.md

configs/cascade_rcnn/README.md

configs/centripetalnet/README.md

configs/cityscapes/README.md

configs/cornernet/README.md

configs/dcn/README.md

configs/deepfashion/README.md

configs/detectors/README.md

configs/double_heads/README.md

configs/dynamic_rcnn/README.md

configs/empirical_attention/README.md

configs/faster_rcnn/README.md

configs/fcos/README.md

configs/foveabox/README.md

configs/fp16/README.md

configs/free_anchor/README.md

configs/fsaf/README.md

configs/gcnet/README.md