docs/boards/orangepi: add Orange Pi 5 Pro bring-up guide

Document the RK3588S firmware handoff, memory and console settings, build configurations, boot procedure, and hardware validation.

Signed-off-by: Emre Cecanpunar <emreleno@gmail.com>

Documentation/platforms/arm64/rk3588/index.rst

@@ -0,0 +1,48 @@
+===============
+Rockchip RK3588
+===============
+
+.. tags:: arch:arm64, chip:rk3588, vendor:rockchip, experimental
+
+.. warning::
+
+   The support for this chip is experimental. Not all features are
+   implemented and they have not been extensively tested by many users.
+
+   Help is wanted if you are interested in supporting a feature or if you've
+   found an issue with any of the implementation! See :doc:`the contributing
+   guidelines </contributing/index>`.
+
+The `Rockchip RK3588 <https://www.rock-chips.com/uploads/pdf/2022.8.26/192/RK3588%20Brief%20Datasheet.pdf>`_
+is an octa-core SoC designed by Rockchip, featuring quad Cortex-A76 cores and quad Cortex-A55 cores.
+It is used on single-board computers like the Orange Pi 5 Pro.
+
+- **CPU:** Octa-core ARMv8.2 (4x Cortex-A76 up to 2.4 GHz + 4x Cortex-A55 up to 1.8 GHz)
+- **Interrupt Controller:** GICv3 (GIC600)
+
+Supported Peripherals
+=====================
+
+======================== =======
+Peripheral               Support
+======================== =======
+UART                     Inherited UART2 debug console.
+GICv3                    Yes
+Timer                    ARM Generic System Timer.
+PSCI                     Yes (System Reset/Reboot via SMC calls to TF-A).
+GPIO                     No
+SPI                      No
+I2C                      No
+USB                      No
+Ethernet                 No
+SDMMC                    No
+======================== =======
+
+Supported Boards
+================
+
+.. toctree::
+   :glob:
+   :maxdepth: 1
+
+   boards/*/*