link to ASCAT loci file

Included a link to the ASCAT documentation under "other files".

Author: malinlarsson

doc/REFERENCES.md

@@ -21,6 +21,8 @@ The following files need to be downloaded:
 
 From our repo, get the [`intervals` list file](https://raw.githubusercontent.com/SciLifeLab/Sarek/master/repeats/wgs_calling_regions.grch37.list). More information about this file in the [intervals documentation](INTERVALS.md)
 
+Description of how to generate the Loci file used in the ASCAT process is described [here](https://github.com/SciLifeLab/Sarek/blob/master/doc/ASCAT.md). 
+
 You can create your own cosmic reference for any human reference as specified below.
 
 ### COSMIC files