docs(transport): improve idle timeout RFC references (#2510)

Author: mxinden

neqo-transport/src/connection/idle.rs

@@ -24,7 +24,9 @@ enum IdleTimeoutState {
 
 #[derive(Debug, Clone)]
 /// There's a little bit of different behavior for resetting idle timeout. See
-/// -transport 10.2 ("Idle Timeout").
+/// -transport 10.1 ("Idle Timeout").
+///
+/// <https://datatracker.ietf.org/doc/html/rfc9000#section-10.1>
 pub struct IdleTimeout {
     timeout: Duration,
     state: IdleTimeoutState,
@@ -61,6 +63,14 @@ impl IdleTimeout {
         // Only reset idle timeout if we've received a packet since the last
         // time we reset the timeout here.
         match self.state {
+            // > An endpoint also restarts its idle timer when sending an
+            // > ack-eliciting packet if no other ack-eliciting packets have
+            // > been sent since last receiving and processing a packet.
+            //
+            // <https://datatracker.ietf.org/doc/html/rfc9000#section-10.1>
+            //
+            // Conversely, given that a packet has been sent since last
+            // receival, don't reset idle timer.
             IdleTimeoutState::AckElicitingPacketSent(_) => {}
             IdleTimeoutState::Init | IdleTimeoutState::PacketReceived(_) => {
                 self.state = IdleTimeoutState::AckElicitingPacketSent(now);