Update new download links for refCOCO series data

Former-commit-id: 1ed6c8106751ac125de9feb08636046901e228a9

README.md

@@ -111,7 +111,7 @@ The training data consists of 4 types of data:
 
 1. Semantic segmentation datasets: [ADE20K](http://data.csail.mit.edu/places/ADEchallenge/ADEChallengeData2016.zip), [COCO-Stuff](https://github.com/nightrome/cocostuff#downloads), [Mapillary](https://www.mapillary.com/dataset/vistas), [PACO-LVIS](https://github.com/facebookresearch/paco/tree/main#dataset-setup), [PASCAL-Part](http://roozbehm.info/pascal-parts/pascal-parts.html)
 
-2. Referring segmentation datasets: refCOCO, refCOCO+, refCOCOg, refCLEF [\[Download\]](https://github.com/lichengunc/refer#download)
+2. Referring segmentation datasets: [refCOCO](https://web.archive.org/web/20220413011718/https://bvisionweb1.cs.unc.edu/licheng/referit/data/refcoco.zip), [refCOCO+](https://web.archive.org/web/20220413011656/https://bvisionweb1.cs.unc.edu/licheng/referit/data/refcoco+.zip), [refCOCOg](https://web.archive.org/web/20220413012904/https://bvisionweb1.cs.unc.edu/licheng/referit/data/refcocog.zip), [refCLEF](https://web.archive.org/web/20220413011817/https://bvisionweb1.cs.unc.edu/licheng/referit/data/refclef.zip) ([saiapr_tc-12](https://web.archive.org/web/20220515000000/http://bvisionweb1.cs.unc.edu/licheng/referit/data/images/saiapr_tc-12.zip)) (Note: the origianl links are down, and we update them with new ones)
 
 3. Visual Question Answering dataset: [LLaVA-Instruct-150k](https://huggingface.co/datasets/liuhaotian/LLaVA-Instruct-150K/blob/main/llava_instruct_150k.json)