Add some basic arabic demo

Yes, the translation is dogshit, I didn't have time to translate it
myself, so here we are, using DeepL

content/demo/code.ar.md

@@ -0,0 +1,21 @@
++++
+title = "عرض كتلة الرمز التوضيحي"
++++
+
+```scss, linenos, linenostart=10, hl_lines=3-4 8-9, hide_lines=2 7
+pre mark {
+
+  display: block;
+
+  color: currentcolor;
+
+}
+
+pre table td:nth-of-type(1) {
+
+  color: #6b6b6b;
+
+  font-style: italic;
+
+}
+```