star docstring fix

src/python/ensembl/tools/anno/transcriptomic_annotation/star.py

@@ -15,6 +15,7 @@
 """
 The STAR (Spliced Transcripts Alignment to a Reference) alignment tool is widely used
 in genomics research for aligning RNA-seq data to a reference genome.
+
 Dobin A, Davis CA, Schlesinger F, et al. STAR: ultrafast universal RNA-seq aligner.
 Bioinformatics. 2013;29(1):15-21. doi:10.1093/bioinformatics/bts635
 """