Better define what Attribute Tables are supposed to be

[u8sand]

DRC-Portals/drc-portals/app/data/contribute/documentation/page.tsx

Lines 155 to 158 in b7e08c3

	Attribute tables are files containing tables that describe the relationship between two entities with one
	entity type on the rows (e.g genes) and another on the columns (e.g tissue types). The intersection of a
	given row and column is then a value defining nature of the relationship between the row entity and the
	column entity e.g. the qualitative score of similarity between a given gene and a given tissue type.

I think we should make this more concrete, especially if we're asking for files serialized in .h5 -- my suggestion is that we adopt the AnnData format. Which is an h5 format that supports dense and sparse matrices and metadata on the columns/on the row identifiers in one file.

It might also be useful to somehow suggest that columns/rows use (or at least link to) some standardized id scheme.