`datasetId` for series not documented for series

The example here:
https://echarts.apache.org/examples/en/editor.html?c=data-transform-filter

uses `datasetId` to reference datasets from series' definitions rather that `datasetIndex`, this does not appear in the documentation.

Start with the linked data-transform-filter example and locate the series documentation covering dataset references. Document that series definitions can use datasetId as well as datasetIndex, with wording consistent with the example. Done means the relevant documentation explains datasetId clearly and matches the demonstrated usage.

Written by the indexing model from the issue text.