`check-docs-drift.sh` scans for `PUNKTFUNK_*` identifiers and asks that
each be documented in docs-site or explicitly baselined. It cannot tell
an env knob from a cbindgen-exported `#define`, so the new
`PUNKTFUNK_MSG_DELIVERY_REPORT` header constant tripped it.
It is a wire message type byte, not a knob an operator can set — same as
every other `PUNKTFUNK_MSG_*`, all of which are already in the baseline.
Added in sorted position beside them.
enricobuehler
ea3c9e1202