Infrastructure: Add comment in reference-tables.js about region gener…

…ation (pull #1088)

So if someone is syncing the array, they don't try and add it

Co-authored-by: Matt King <a11yThinker@Gmail.com>

scripts/reference-tables.js

@@ -66,6 +66,7 @@ const ariaRoles = [
   'progressbar',
   'radio',
   'radiogroup',
+  // 'region', Region is generated differently from other roles
   'row',
   'rowgroup',
   'rowheader',