message: Fix link to billing page
diff: p.Type
  | Up to 100 private blocks
  .Square__price Free
  - a.Square.Square--premium(href="/settings/premium")
  + a.Square.Square--premium(href="/settings/billing")
  h4.Type.Type--size-h4.Type--premium Premium
  .Square__features
  p.Type Unlimited public blocks
  