bpo-29506: Clarify deep copy note in copy module

The reference to administrative data was confusing to readers,
so this simplifies the note to explain that deep copying may copy
more then you intended, such as data that you expected to be
shared between copies.
diff --git a/Misc/ACKS b/Misc/ACKS
index 70678c3..962a3c7 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
Binary files differ