clarify what name values can be used

draft-ietf-quic-qlog-h3-events.md

@@ -521,9 +521,14 @@ H3CancelPushFrame = {
 
 ### H3SettingsFrame
 
-Where an individual setting is not known, the name value of "unknown"
-can be used and the value captured in the raw_type field; a
-numerical value without variable-length integer encoding.
+The settings field can contain zero or more entries. Each setting has a name
+field, which corresponds to Setting Name as defined (or as would be defined if
+registered) in the the "HTTP/3 Settings" registry maintained at
+<https://www.iana.org/assignments/http3-parameters>. 
+
+An endpoint that receives unknown settings is not able to log a specific name.
+Instead, the name value of "unknown" can be used and the value captured in the
+raw_type field; a numerical value without variable-length integer encoding.
 
 ~~~ cddl
 H3SettingsFrame = {