fix --progress display description, fixes #7180

src/borg/archiver/create_cmd.py

@@ -552,9 +552,9 @@ class CreateMixIn:
         is used to determine changed files quickly uses absolute filenames.
         If this is not possible, consider creating a bind mount to a stable location.
 
-        The ``--progress`` option shows (from left to right) Original, Compressed and Deduplicated
-        (O, C and D, respectively), then the Number of files (N) processed so far, followed by
-        the currently processed path.
+        The ``--progress`` option shows (from left to right) Original and (uncompressed)
+        deduplicated size (O and U respectively), then the Number of files (N) processed so far,
+        followed by the currently processed path.
 
         When using ``--stats``, you will get some statistics about how much data was
         added - the "This Archive" deduplicated size there is most interesting as that is