Update draft-ietf-quic-recovery.md

Co-Authored-By: Jana Iyengar <jri.ietf@gmail.com>

draft-ietf-quic-recovery.md

@@ -587,7 +587,7 @@ In addition to sending data in the packet number space for which the timer
 expired, the sender SHOULD send ack-eliciting packets from other packet
 number spaces with in-flight data, coalescing packets if possible.
 
-When only sending a single packet on PTO, senders can skip a packet number to
+If the sender sends a single packet on PTO, it can skip a packet number to
 elicit a faster acknowledgement.
 
 When the PTO timer expires, and there is new or previously sent unacknowledged