Broken link for SPI Library documentation in the learning section

[fabianegli]

Some links in the docs are stale. One example is the link to

https://docs.arduino.cc/language-reference/en/functions/communication/spi/

on https://docs.arduino.cc/learn/communication/spi/

The correct link would be:

https://reference.arduino.cc/reference/en/language/functions/communication/spi/

[fabianegli]

This seems to be the wrong repository to apply changes. The affected file is https://github.com/arduino/docs-content/edit/main/content/learn/05.communication/02.spi/spi.md and the broken link is https://www.arduino.cc/en/reference/SPI which is then apparently redirected to the wrong URL.

Closing this issue here because the PR lives in a different repo. See arduino/docs-content#2335