Update style check instructions in README
@@ -53,7 +53,7 @@ the code Django includes for this purpose: `SECRET_KEY=$(python -c "from django.
## Tests
```
-pycodestyle --exclude=migrations,settings.py,venv,lib_oval.py,test_ubuntu.py,test_suse.py --max-line-length=100 .
+pycodestyle --exclude=migrations,settings.py,venv,lib_oval.py,test_ubuntu.py,test_suse.py,test_data_source.py --max-line-length=100 .
DJANGO_DEV=1 pytest
```
To skip tests which require internet connection:
