Doc clarification about Atomizer and Indexifier extensions order declaration in the pipeline

When using the Atomizer extension in conjunction with the Indexifier extension, it is not clearly stated in the doc that the former must be declared after the latter in the pipeline.

I discovered that I had to declare them in this way, in order to get valid permalinks and ids in the feed entries. It really is not a big deal and it might be a valid behavior but then, IMO, it would be cool to have this insight in the doc.