documents: Flask-OAuthlib upgrade fix
- Fixes API changes related to Flask-OAuthlib upgrade.
- Some PEP257 love.
Co-authored-by: Lars Holm Nielsen <lars.holm.nielsen@cern.ch>
Signed-off-by: Konstantinos Kostis <konstantinos.kostis@cern.ch>
Reviewed-by: Lars Holm Nielsen <lars.holm.nielsen@cern.ch>