FAQ: why is there less metadata in my object?

I think this FAQ is possibly unnecessary, in that I don't know that it will even be frequently asked! I would say we don't need to implement this unless we get the question. But just in case...

In the merged AnnData objects, we necessarily had to sacrifice some amount of metadata because of challenges with data format conversions from R -> python. Most, but not all, of this metadata is available in the `single_cell_metadata.tsv` that comes with the download. We might consider an FAQ about why there is relatively less metadata in AnnData compared to SCE merged objects, and the answer is because of technical differences in object formatting.

Review the proposed FAQ wording about reduced metadata in merged AnnData objects and the R-to-Python format conversion described in the issue. Check the accompanying single_cell_metadata.tsv reference, then determine whether the FAQ should be added; done means documenting the explanation and where the remaining metadata can be found.

Written by the indexing model from the issue text.