Fix markdown for eval instructions

reports/assist-mini/README.md

@@ -17,7 +17,7 @@ local models which have not performed that well on the `assist` dataset.
 
 Prepare dev environment:
 
-``bash
+```bash
 $ python3 -m venv venv
 $ source venv/bin/activate
 $ pip3 install -r requirements_dev.txt