Added period because grammar is important/

README.md

 ### Themis Debiasing System
 
 Extended Paper [here](https://arxiv.org/abs/2002.09799).
-Slides [here](https://gitlab.cs.washington.edu/uwdb/project_themis_debias/tree/master/OrrSIGMOD2020.pdf)
+Slides [here](https://gitlab.cs.washington.edu/uwdb/project_themis_debias/tree/master/OrrSIGMOD2020.pdf).
 
 #### A Quick Note
 This is not a production quality repo. I've tried to provide instructions below but realize that some of the code is messy. Also, all of my instruction files for run commands use the fish shell.