Added citation

index.md

@@ -60,4 +60,20 @@ Published in __IEEE Transactions on Robotics (T-RO)__
 </p>
 
 ## Citation
-(Coming soon)
+```
+S. Ruan, W. Liu, X. Wang, X. Meng and G. S. Chirikjian, "PRIMP: PRobabilistically-Informed Motion Primitives for Efficient Affordance Learning from Demonstration," in IEEE Transactions on Robotics, doi: 10.1109/TRO.2024.3390052.
+```
+
+BibTex
+```
+@ARTICLE{10502164,
+  author={Ruan, Sipu and Liu, Weixiao and Wang, Xiaoli and Meng, Xin and Chirikjian, Gregory S.},
+  journal={IEEE Transactions on Robotics}, 
+  title={PRIMP: PRobabilistically-Informed Motion Primitives for Efficient Affordance Learning from Demonstration}, 
+  year={2024},
+  volume={},
+  number={},
+  pages={1-20},
+  keywords={Trajectory;Robots;Probabilistic logic;Planning;Affordances;Task analysis;Manifolds;Learning from Demonstration;Probability and Statistical Methods;Motion and Path Planning;Service Robots},
+  doi={10.1109/TRO.2024.3390052}}
+```