Fix link to backends explanation

[kinow]

Hi,

The original link is redirected in their website, and the tutorial linked doesn't mention backends. I think they moved it to the user guide explanations section.

Bruno

[kinow]

Sphinx has an extension to check for links ¹, there may be some GitHub action or another plug-in that scans the links in the book and reports if any HTTP status reported is not 20x. Which could help identifying issues like this earlier.

Footnotes

1. https://www.sphinx-doc.org/en/master/_modules/sphinx/builders/linkcheck.html ↩

[rougier]

Thanks for the correction. As for the linkcheck, I need to find the time to implement it as an action.