Missing documentation for HydratingIteratorIterator

[froschdesign]

The entire iterator feature needs some explanation and code examples.

• Laminas\Hydrator\Iterator\HydratingArrayIterator
• Laminas\Hydrator\Iterator\HydratingIteratorInterface
• Laminas\Hydrator\Iterator\HydratingIteratorIterator

[settermjd]

I can get on that, just as soon as I'm finished the content restructure. Should be able to get to it next week. It'd be an interesting challenge, I think.