Update index.md

[thodson-usgs]

Remove fsspec from xr.open_dataset usage example.

Did I misunderstand something? I thought we could just

ds = xr.open_dataset('combined.json', ...)

[TomNicholas]

Oh right yes - with engine='kerchunk' you don't need the fsspec mapper (because the kerchunk backend engine creates the mapper for you.

Soon I want to update these top-level examples to use icechunk instead though, which would just be

xr.open_zarr(icechunkstore)

[norlandrhagen]

Merging this for now, with the goal of replacing the default examples with icechunk