Adding paper link

Added in link to the research paper OPUS-MT – Building open translation services for the World

README.md

@@ -30,6 +30,7 @@ license: cc-by-4.0
 - **License:** CC-BY-4.0
 - **Resources for more information:**
   - [GitHub Repo](https://github.com/Helsinki-NLP/OPUS-MT-train)
+  - [Paper](https://aclanthology.org/2020.eamt-1.61/)
 
 
 ## Uses