specs: Discuss which field and codec we're using

[evan-forbes]

Currently, we're using the leopard codec and GF8 and GF16 fields when we erasure our data, but afaiu, we don't specify this anywhere. We should mention that we are actually switching to GF8 when the square size is 128 or smaller, and then only switch to GF16 when needed.

[rootulp]

klauspost/reedsolomon uses leopardGF16 when total shards > 256 which I think occurs when squareSize >= 8 because: squareSize=8 means EDS of width 16 so total shares of 16 * 16 = 256. @evan-forbes am I misinterpreting something?

[evan-forbes]

am I misinterpreting something?

its determined by row or column size