How-to-guide.md

@@ -13,4 +13,6 @@ The solution is to navigate to the folder `.../ete3/ncbi_taxonomy/SQLite-Levensh
 The folder `ete3` is located within the `.../lib/pythonX.X/site-package` folder and not where the binary file is. 
 
 
-Reference : https://github.com/etetoolkit/ete/issues/173
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+Reference : https://github.com/etetoolkit/ete/issues/173
+
+If it remains unclear : https://gitlab.mbb.univ-montp2.fr/edna/custom_reference_database/-/issues/4
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