Link the email, X and FFmpeg guides from the README

Author: YKLovePython

README.md

@@ -140,7 +140,10 @@ Step-by-step guides with measured quality numbers:
 [Discord 20 MB](https://YKLovePython.github.io/halfsize/discord/) ·
 [WhatsApp 16 MB](https://YKLovePython.github.io/halfsize/whatsapp/) ·
 [WeChat 20 MB](https://YKLovePython.github.io/halfsize/wechat/) ·
+[email attachments](https://YKLovePython.github.io/halfsize/email/) ·
+[X / Twitter](https://YKLovePython.github.io/halfsize/twitter/) ·
 [any 20 MB limit](https://YKLovePython.github.io/halfsize/20mb/) ·
+[FFmpeg target size](https://YKLovePython.github.io/halfsize/ffmpeg-compress-to-size/) ·
 [compress without uploading](https://YKLovePython.github.io/halfsize/offline/).
 
 ### Use it from an agent

README.zh-CN.md

@@ -133,6 +133,9 @@ npx halfsize --web
 附实测画质的分平台教程：
 [微信 20 MB](https://YKLovePython.github.io/halfsize/zh/wechat/) ·
 [任意 20 MB 限制](https://YKLovePython.github.io/halfsize/zh/20mb/) ·
+[邮件附件](https://YKLovePython.github.io/halfsize/zh/email/) ·
+[X / Twitter](https://YKLovePython.github.io/halfsize/zh/twitter/) ·
+[ffmpeg 指定大小](https://YKLovePython.github.io/halfsize/zh/ffmpeg-compress-to-size/) ·
 [Discord 20 MB](https://YKLovePython.github.io/halfsize/discord/) ·
 [WhatsApp 16 MB](https://YKLovePython.github.io/halfsize/whatsapp/) ·
 [本地压缩不上传](https://YKLovePython.github.io/halfsize/zh/offline/)。