Update draft-ietf-quic-recovery.md

Author: ianswett

draft-ietf-quic-recovery.md

@@ -420,9 +420,9 @@ expires.
 
 If no new data or unacknowledged data is available to send, a retransmittable
 frame SHOULD be sent.  Sending a retransmittable frame ensures that any in
-flight packets are acknowledged or declared lost in a timely manner,
-potentially preventing a deadlock if all in flight packets contain no data
-that needs to be retransmission.
+flight packets are acknowledged or declared lost in a timely manner.
+Otherwise, a deadlock results if there is no available congestion window and
+all in flight packets contain no data that can be retransmitted.
 
 A sender may not know that a packet being sent is a tail packet.  Consequently,
 a sender may have to arm or adjust the TLP timer on every sent retransmittable