fix(docs): Updates SPI reference link in documentation

[eMUQI]

Description of Change

Replaces an outdated SPI reference link with the updated URL in the documentation. This ensures users are directed to the correct and maintained Arduino SPI reference.

Related links

https://docs.espressif.com/projects/arduino-esp32/en/latest/api/spi.html
https://docs.arduino.cc/language-reference/en/functions/communication/SPI/

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