Update citations

Author: cemitch99

src/particles/distribution/SpinvMF.H

@@ -31,9 +31,11 @@ namespace impactx::distribution
          * The algorithm used here is a simplification of the algorithm described in:
          * C. Pinzon and K. Jung, "Fast Python sampler of the von Mises Fisher distribution", in the special
          * case of the 2-sphere.  Additional references used include:
-         * K. V. Mardia and P. E. Jupp, Directional Statistics, Wiley, 1999
+         *
+         * K. V. Mardia and P. E. Jupp, Directional Statistics, Wiley, 1999;
          * S. Kang and H-S. Oh, "Novel sampling method for the von Mises-Fisher distribution", Stat.
-         * and Comput. 34, 106 (2024), https://doi.org/10.1007/s11222-024-10419-3
+         * and Comput. 34, 106 (2024), https://doi.org/10.1007/s11222-024-10419-3.
+         *
          * Return sampling from a vMF distribution.
          *
          * @param mux,muy,muz components of a unit vector specifying the mean direction