Update DOIs where possible.

doc/joss_paper/paper.bib

@@ -6,7 +6,8 @@
   number={2},
   pages={8--12},
   year={2009},
-  publisher={IEEE}
+  publisher={IEEE},
+  doi={10.1109/MIS.2009.36}
 }
 
 @inproceedings{mlpack2011,
@@ -15,7 +16,8 @@
   title={{mlpack: A Scalable C++ Machine Learning Library}},
   booktitle={{BigLearning: Algorithms, Systems, and Tools for Learning at
               Scale}},
-  year = 2011
+  year = 2011,
+  doi = {10.1.1.676.5625}
 }
 
 @article{mlpack2013,
@@ -40,7 +42,8 @@
   author={Sanderson, C. and Curtin, R.R.},
   journal={Journal of Open Source Software},
   year={2016},
-  publisher={Journal of Open Source Software}
+  publisher={Journal of Open Source Software},
+  doi={10.21105/joss.00026}
 }
 
 @misc{xianyi2018openblas,
@@ -54,7 +57,7 @@
   title={{NVBLAS Library}},
   author={{NVIDIA}},
   year={2015},
-  howpublished={\ur;{http://docs.nvidia.com/cuda/nvblas}}
+  howpublished={\url{http://docs.nvidia.com/cuda/nvblas}}
 }
 
 @inproceedings{curtin2013tree,