Docs: highlight file name

README.md

@@ -53,7 +53,7 @@ The VIPS models available will vary between deployments of VIPSCore-Python. They
 ```sh
 pip install -r models.txt
 ```
-If a model has been updated, it needs to be installed again, running the same command. Make sure to update any version tags in the models.txt beforehand.
+If a model has been updated, it needs to be installed again, running the same command. Make sure to update any version tags in the `models.txt` beforehand.
 
 ## Development