Update Wolf tutorial with the OBITools3

Wolf-tutorial-with-the-OBITools3.md

@@ -127,6 +127,10 @@ For EMBL files, you can give the path to a directory with several EMBL files.
 
 		wget https://ftp.ncbi.nlm.nih.gov/pub/taxonomy/taxdump.tar.gz
 
+  Check the md5, as files downloaded from the NCBI are often corrupted on some networks. Compare https://ftp.ncbi.nlm.nih.gov/pub/taxonomy/taxdump.tar.gz.md5 with:
+
+		md5sum taxdump.tar.gz
+
 4. Import the taxonomy in the DMS:
 
 		obi import --taxdump taxdump.tar.gz wolf/taxonomy/my_tax