Allow specifying rtl in both page and layout

[neveler]

This is an enhancement or feature.

Summary

Allow specifying rtl in both page and layout.

---
title: xxx
locale: ar
direction: rtl
---

xxx

Move the dir attribute from the body to the html.

minimal-mistakes/assets/js/_main.js

Line 155 in 5786c35

var isRTL = document.documentElement.getAttribute("dir") === "rtl";