Updates to Dask page in Xarray docs (#9495)

* First pass at updates to Dask page in Xarray docs

* cleanup

* [pre-commit.ci] auto fixes from pre-commit.com hooks

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* Fix internal references

* Apply suggestions from code review

Co-authored-by: Tom Nicholas <[email protected]>
Co-authored-by: Stephan Hoyer <[email protected]>

* Update Dask Array image

* Updates after review

* [pre-commit.ci] auto fixes from pre-commit.com hooks

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* Some edits

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Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Tom Nicholas <[email protected]>
Co-authored-by: Stephan Hoyer <[email protected]>
Co-authored-by: Deepak Cherian <[email protected]>

Author: 5 people