Add proto comments

llo/plugin_codecs.proto

@@ -13,6 +13,10 @@ message LLOObservationProto {
 	bool shouldRetire = 2;
 	int64 unixTimestampNanoseconds = 3;
 	repeated uint32 removeChannelIDs = 4;
+    // Maps are safe to use here because Observation serialization does not
+    // need to be deterministic. Non-deterministic map serialization is
+    // marginally more efficient than converting to tuples and guarantees
+    // uniqueness.
 	map<uint32, LLOChannelDefinitionProto> updateChannelDefinitions = 5;
 	map<uint32, bytes> streamValues = 6;
 }
@@ -28,8 +32,7 @@ message LLOStreamObservationProto {
     bytes value = 2;
 }
 
-// NOTE: Use of repeated tuple instead of maps for more reliable determinstic
-// serialization
+// NOTE: Outcome must serialize deterministically, hence use of repeated tuple instead of maps
 message LLOOutcomeProto {
 	string lifeCycleStage = 1;
 	int64 ObservationsTimestampNanoseconds = 2;