chore: update readme

Author: zhyupe

README.md

@@ -1,2 +1,19 @@
 # ffxiv-opcode-worker
 This repository contains workflows that generate opcode files for different purposes
+
+## About the opcodes
+存储 opcode 的文件 (cn-opcodes.csv) 是 Google Docs 上一个电子表格的镜像。所有修改都应当在原始文件上进行，请不要向
+该文件提交 PR。
+
+如果您认为某个**当前版本**的 opcode 是错误的，或者想要更新对应的 WireShark 过滤器，请提交 Issue 并提供 Wireshark
+的截图（如果 opcode 是通过字节码发现的，请提供 IDA 截图）。请记得抹去截图中如 ID、昵称、账号等敏感信息。由于过期的
+opcode 没有实际用途，历史版本及已公告更新时间的版本将不再接受修正。相关历史版本的 opcode 可能被移除。
+
+The opcodes file (cn-opcodes.csv) is a mirror to a spreadsheet on Google Docs. So any PR to the csv file 
+will be closed as they should be updated in the original file. 
+
+If you think any opcode is incorrect in **CURRENT GAME VERSION** or want to update WireShark filters, 
+please open an issue. Screenshots of Wireshark (or IDA if you discovered an opcode from bytecode) are 
+required. Please remember to erase any sensitive data like your ID, nickname, account, etc. Corrections 
+would not be accepted if the correlated game version expired or a new patch is scheduled since old opcodes 
+are actually useless and may be removed any time.