Rename guestbook.html to index.html

main.py

@@ -40,7 +40,7 @@ async def new_message(event):
 
     entry += '\n\n{}\n\n'.format(data['message'])
 
-    with open('data/guestbook.html', 'a') as f:
+    with open('data/html/index.html', 'a') as f:
         f.write(entry)
 
     await event.reply('Entry added to t0.vc/g')