add citation

Author: sblunt

docs/index.rst

@@ -31,7 +31,7 @@ create an `issue on GitHub <https://github.com/sblunt/orbitize/issues>`_.
 Attribution:
 ++++++++++++
 
-* If you use ``orbitize`` in your work, please cite `Blunt et al (2019) <https://ui.adsabs.harvard.edu/abs/2019arXiv191001756B/abstract>`_.
+* If you use ``orbitize`` in your work, please cite `Blunt et al (2019) <https://ui.adsabs.harvard.edu/abs/2019arXiv191001756B/abstract>`_ and `Blunt et al (2024) <https://ui.adsabs.harvard.edu/abs/2024JOSS....9.6756B/abstract>`_
 * If you use the OFTI algorithm, please also cite `Blunt et al (2017) <https://ui.adsabs.harvard.edu/#abs/2017AJ....153..229B/abstract>`_. 
 * If you use the Affine-invariant MCMC algorithm from ``emcee``, please also cite `Foreman-Mackey et al (2013) <https://ui.adsabs.harvard.edu/abs/2013PASP..125..306F/abstract>`_. 
 * If you use the parallel-tempered Affine-invariant MCMC algorithm from ``ptemcee``, please also cite `Vousden et al (2016) <https://ui.adsabs.harvard.edu/abs/2016MNRAS.455.1919V/abstract>`_.