Improve pandoc pdf macro for CJK by using M+ font

hosts/home.nix

@@ -123,7 +123,7 @@ in
       # pandoc macro
       # pandoc document.md -> pandoc document.md -o document.pdf ...
       function pdf {
-        pandoc $1 -o ''${1%.*}.pdf -V colorlinks=true -V linkcolor=blue
+        pandoc $1 -o ''${1%.*}.pdf --pdf-engine=xelatex -V mainfont="mplus-1c-medium" -V colorlinks=true -V linkcolor=blue
       }
 
       # Change to directory when exiting ranger with Q