RTL is supported quite well, I think. I'm not sure as I don't have any idea what it means in Hebrew )
Here how the book part from an article you've send looks:
P.S. Now I see I've checked, and it shows wrong. Sorry to bother, you can ignore my post, ask developers or create an issue on github. )
P.P.S. As I see even based on my assumptions it does not look RTL, just LTR with to-the-right-side alignment, so RTL might not be fully supported.