[QUIC]update comments on QUIC connection options protos (#28933)

Signed-off-by: Renjie Tang <renjietang@google.com>

Mirrored from https://github.com/envoyproxy/envoy @ 473cb074a4cb874d952b8186d6ad5a7f0dacab69

envoy/config/core/v3/protocol.proto

@@ -95,10 +95,12 @@ message QuicProtocolOptions {
   // If absent, use the default keepalive behavior of which a client connection sends PINGs every 15s, and a server connection doesn't do anything.
   QuicKeepAliveSettings connection_keepalive = 5;
 
-  // An array of QUIC connection options represented in a serialized string, separated by commas.
+  // A comma-separated list of strings representing QUIC connection options defined in
+  // `QUICHE <https://github.com/google/quiche/blob/main/quiche/quic/core/crypto/crypto_protocol.h>` and to be sent by upstream connections.
   string connection_options = 6;
 
-  // An array of QUIC client connection options represented in a serialized string, separated by commas.
+  // A comma-separated list of strings representing QUIC client connection options defined in
+  // `QUICHE <https://github.com/google/quiche/blob/main/quiche/quic/core/crypto/crypto_protocol.h>` and to be sent by upstream connections.
   string client_connection_options = 7;
 }