Merge pull request #148 from oesteban/docs/fix-topup-reference

DOC: Add FSL ``topup`` reference in citation boilerplate

Author: oesteban

dmriprep/data/boilerplate.bib

@@ -356,3 +356,17 @@ @article{posse_t2s
     volume = 42,
     year = 1999
 }
+
+
+@article{topup,
+    title = {How to correct susceptibility distortions in spin-echo echo-planar images: application to diffusion tensor imaging},
+    volume = {20},
+    issn = {1053-8119},
+    shorttitle = {How to correct susceptibility distortions in {SE} {EPIs}},
+    doi = {10.1016/S1053-8119(03)00336-7},
+    number = {2},
+    journal = {NeuroImage},
+    author = {Andersson, Jesper L.R. and Skare, Stefan and Ashburner, John},
+    year = {2003},
+    pages = {870--888},
+}