I am using the markdown editor StackEdit. I want my article to be written in 2 different modes: Certain rows to be written from right-to-left and some others to be left-to-right. Is there such a possible way to do it? I see in the settings menu that I can change the direction but only for the whole document.
It's possible but requires quite a bit of programming. StackEdit accepts custom extensions where you can add extra functionality to it.
Custom scripts are added at the very end of Settings » Extensions: