cs: clarify where 24 comes from in maxMsgSizeBytes (wal.go)

consensus/wal.go

@@ -20,7 +20,10 @@ import (
 
 const (
 	// amino overhead + time.Time + max consensus msg size
-	// TODO: Can we clarify better where 24 comes from precisely?
+	//
+	// q: where 24 bytes are coming from?
+	// a: cdc.MustMarshalBinaryBare(empty consensus part msg) = 14 bytes. +10
+	// bytes just in case amino will require more space in the future.
 	maxMsgSizeBytes = maxMsgSize + 24
 
 	// how often the WAL should be sync'd during period sync'ing