Minor docs improvements

[seldon]

Hi, I'd like to point out a couple of (trivial) documentation-related issues:

• In itemloaders/__init__.py, itemloaders/processors.py: module-level docstrings reference docs/topics/loaders.rst, but AFAICS this file doesn't exists (maybe a leftover of a previous version?);
• This section could be refined a little bit.

If there is interest, I could suggest a patch.

[wRAR]

AFAICS this file doesn't exists (maybe a leftover of a previous version?)

It's a leftover from time when this was a part of Scrapy (https://github.com/scrapy/scrapy/blob/master/docs/topics/loaders.rst)

If there is interest, I could suggest a patch.

Yes please!

[Gallaecio]

#106