readme - update

README.md

@@ -72,9 +72,10 @@ Usage: digiarch init [OPTIONS] AVID_DIR
   The directory is checked to make sure it has the structure expected of an
   AVID archive.
 
-  The --import option allows to import OriginalFiles from a files.db database
-  generated by version v4.1.12 of digiarch (acacore v3.3.3). MasterFiles are
-  added as well, if present in the database.
+  The --import option allows to import original and master files from a
+  files.db database generated by version v4.1.12 of digiarch (acacore v3.3.3).
+  A pre-acacore version of the database can also be used if it contains a
+  'Files' table with a 'path' column, but some master files may be missing.
 
 Options:
   --import FILE  Import an existing files.db