message: docs: update attribute-binding.md to correctly describe [attr.binding] rules
  PR Close
diff: @@ -34,7 +34,7 @@ Then, you set the attribute value with an expression that resolves to a string.
  <div class="alert is-helpful">
  -When the expression resolves to `null`, Angular removes the attribute altogether.
  +When the expression resolves to `null` or `undefined`, Angular removes the attribute altogether.
  </div>
  