Update RandWire-WS, Res2Net, and MultiGrain papers

Author: kobiso

README.md

@@ -20,6 +20,7 @@ Leaderboards are provided in the below link for better accessibility and usabili
 - **181126.** Update [A^2-Nets](https://arxiv.org/abs/1810.11579v1), [ResNet variants from GLUON-CV](https://gluon-cv.mxnet.io/model_zoo/classification.html#id184), and [ChannelNets](https://arxiv.org/pdf/1809.01330v1.pdf)
 - **181130.** Update [FishNet](https://papers.nips.cc/paper/7356-fishnet-a-versatile-backbone-for-image-region-and-pixel-level-prediction.pdf) and [osmr/imgclsmob repo](https://github.com/osmr/imgclsmob)
 - **190326.** Update [SKNet](https://arxiv.org/abs/1903.06586) paper
+- **190505.** Update [RandWire-WS](https://arxiv.org/abs/1904.01569), [Res2Net](https://arxiv.org/abs/1904.01169), and [MultiGrain](https://arxiv.org/abs/1902.05509) papers
 
 ### Stanford Online Products Retrieval Leaderboard
 - **181222.** Create the [Stanford Online Products Retrieval Leaderboard](https://kobiso.github.io/Computer-Vision-Leaderboard/sop)