Add RTL Support (#4886)

Signed-off-by: Hamed Faramarzi <hamed.faramarzi@gmail.com>
Co-authored-by: Hamed Faramarzi <hamed.faramarzi@gmail.com>
Co-authored-by: iBug <git@ibugone.com>

_sass/minimal-mistakes/_syntax.scss

@@ -13,6 +13,10 @@ figure.highlight {
   line-height: 1.8;
   border-radius: $border-radius;
 
+  [dir=rtl] & {
+    direction: ltr;
+  }
+
   > pre,
   pre.highlight {
     margin: 0;