docs: audit accounting endpoint stubs

REDESIGN.md

@@ -894,7 +894,10 @@ Accounting is a maybe.  It has a separate protocol domain, but in many setups it
 may be small enough to stay as an in-process provider.  A process boundary only
 makes sense if accounting grows into a real persistent service with charges,
 holds, notes, audit records, and recovery behavior that should be isolated from
-connection handlers.
+connection handlers.  The legacy Accounting NCPs (`23/150` through `23/153`) can
+also be used by accounting/print servers to hold, charge, and note service work,
+so future queue-printing integration should call into the accounting provider
+rather than duplicating balance/hold/audit behavior inside the queue provider.
 
 ### Poor process candidates