Fix TLS too

draft-ietf-quic-tls.md

@@ -678,10 +678,10 @@ been received or sent, an endpoint starts a timer.  For 0-RTT keys, which do not
 carry CRYPTO frames, this timer starts when the first packets protected with
 1-RTT are sent or received.  To limit the effect of packet loss around a change
 in keys, endpoints MUST retain packet protection keys for that encryption level
-for at least three times the current Retransmission Timeout (RTO) interval as
-defined in {{QUIC-RECOVERY}}.  Retaining keys for this interval allows packets
-containing CRYPTO or ACK frames at that encryption level to be sent if packets
-are determined to be lost or new packets require acknowledgment.
+for at least three times the current Probe Timeout (PTO) interval as defined in
+{{QUIC-RECOVERY}}.  Retaining keys for this interval allows packets containing
+CRYPTO or ACK frames at that encryption level to be sent if packets are
+determined to be lost or new packets require acknowledgment.
 
 Though an endpoint might retain older keys, new data MUST be sent at the highest
 currently-available encryption level.  Only ACK frames and retransmissions of