Broken link in README

[adamjstewart]

The following link in the README is broken:

It is also possible to parallelise at a CI-level using strategies, see example

Should probably link to a specific commit of what the file used to look like before it was removed.

[alex-treebeard]

they pass notebooks to the GitHub action matrix parameter...here's their current version

The downside of this approach is you will have to duplicate the running of setup steps for each notebook (e.g. pip install)

Will fix this broken link/improve docs...