documentation: properly calculate child offset for 11bit result counts.

documentation: properly calculate child offset for 11bit result counts.

Instead of fetching the exact same value twice and then forgetting to
patch it in one case, let's just reuse the patched value.

Hmmmm, this was a bug! And no tests caught it! Though, it was rather
unlikely to be hit in practice as the 100+th result would be cut away,
thus not even giving the user a hint to type futther.