docs: raspberrrypi: rpi_pico: Fix broken RP2040 datasheet link

The RP2040 datasheet link in the rpi_pico board documentation was broken.

It has been updated to point to the correct location.

This change ensures consistency and prevents confusion, while keeping the
useful reference to the official RP2040 documentation.

Signed-off-by: Gaetan Perrot <gaetan.perrot@spacecubics.com>

Author: moonlight83340

boards/raspberrypi/rpi_pico/doc/index.rst

@@ -4,7 +4,7 @@ Overview
 ********
 
 The `Raspberry Pi Pico`_ and Pico W are small, low-cost, versatile boards from
-Raspberry Pi. They are equipped with an `RP2040 <RP2040_Datasheet>`_ SoC, an on-board LED,
+Raspberry Pi. They are equipped with an `RP2040 <RP2040 Datasheet_>`_ SoC, an on-board LED,
 a USB connector, and an SWD interface.
 
 The Pico W additionally contains an `Infineon CYW43439`_ 2.4 GHz Wi-Fi/Bluetooth module.