Update Readme.md

Author: fsx950223

tensorflow_addons/losses/README.md

@@ -9,6 +9,7 @@
 | npairs | @WindQAQ | [email protected] |
 | sparsemax_loss | @AndreasMadsen | [email protected] |
 | triplet |   |  |
+| giou_loss | @who who who  | [email protected] |
 
 ## Components
 | Submodule | Loss  | Reference               |
@@ -20,6 +21,7 @@
 | npairs | NpairsMultilabelLoss | http://www.nec-labs.com/uploads/images/Department-Images/MediaAnalytics/papers/nips16_npairmetriclearning.pdf |
 | sparsemax_loss | SparsemaxLoss |  https://arxiv.org/abs/1602.02068 |
 | triplet | TripletSemiHardLoss | https://arxiv.org/abs/1503.03832       |
+| giou_loss | GIOULoss | https://giou.stanford.edu/GIoU.pdf       |
 
 
 ## Contribution Guidelines