Clarify some code comments

src/index.js

@@ -46,7 +46,7 @@ function formatAttachment(attachment) {
   });
 }
 
-// "Forward all messages not starting in prefix"
+// If the alwaysReply option is set to true, send all messages in modmail threads as replies, unless they start with the prefix
 if (config.alwaysReply) {
   bot.on('messageCreate', msg => {
     if (! msg.channel.guild) return;

src/threads.js

@@ -3,6 +3,9 @@ const utils = require('./utils');
 const jsonDb = require('./jsonDb');
 const config = require('../config');
 
+// If the following messages would be used to start a thread, ignore it instead
+// This is to prevent accidental threads from e.g. irrelevant replies after the thread was already closed
+// or replies to the greeting message
 const accidentalThreadMessages = [
   'ok',
   'okay',