Update README.md

Author: shawntanzk

README.md

@@ -103,6 +103,9 @@ Markers are referenced by enembl ID using an [identifiers.org URL scheme](https:
 
 ensembl gene file templates are used to generate mirror files, which act as source files for import generation, so that only referenced markers end up in the release files.
 
+### Reference Gene Files
+
+GTF files used as reference for BDSO can be found in this [google drive folder](https://drive.google.com/drive/folders/1rOYwiIxGgEolWsO3a-7g6rxUefsXIcKB)