Making better use of cross-referencing #611
Description
As discussed in #609, there is quite a bit of scope for making better use of Myst capabilities for cross-referencing with external documentation.
We are currently defining some site-wide references in our upstream config file to a few sets of documentation including Xarray, Matplotlib, and our own Foundations.
It would be possible to go through the book and replace a lot of full URL links to documentation pages with cross-references. And example is in the overview section of the Xarray intro notebook.
One advantage of doing this would be more stable links. If an upstream doc site reorganizes its URLs, as long as the intersphinx references stay put, the links in our book will still resolve correctly.