建议支持把 .MKD 后缀识别为 Markdown 文件

我的使用习惯是 .MD 后缀用记事本打开，.MKD 后缀用 Typora 打开，显然 .MARKDOWN 的后缀太长了，使用起来不太方便。

Suggest support for recognizing .MKD suffixes as Markdown files.

My habit is to open the .MD extension in Notepad and the .MKD extension in Typora, but obviously the .MARKDOWN extension is too long and not very convenient to use.