docs: duo256m add riscv and arm switch

Author: carbonfix

docs/duo/getting-started/duo256m.md

@@ -27,7 +27,7 @@ Milk-V is the Authorised Global Distributor of the SG2002 chips. You can buy sam
 
 ## Duo256M GPIO Pinout
 
-<Image src='/docs/duo/duo/duo-pinout-01.webp' maxWidth='50%' align='center' />
+<Image src='/docs/duo/duo256m/duo256m-pinout-01.webp' maxWidth='50%' align='center' />
 
 ### GPIO pin mapping
 
@@ -75,3 +75,22 @@ Milk-V is the Authorised Global Distributor of the SG2002 chips. You can buy sam
 </div>
 
 The logic level of `GP26` and `GP27` pins is 1.8V, and the logic level of other GPIO pins is 3.3V logic level.
+
+## Duo256M User Guide
+
+### RISC-V and ARM switching
+
+The large core of Duo256M can choose to use RISC-V or ARM processor. The RISC-V core is used by default. You can switch to the ARM core by shorting physical pin 35 (Boot-Switch) and GND. If you find that Duo256M cannot start normally during use, please first check whether the core currently used is consistent with the firmware used.
+
+<Image src='/docs/duo/duo256m/duo256m-arm-riscv-switch.webp' maxWidth='50%' align='center' />
+
+If the debug serial port is connected, you can see in the first line of the boot log that starting with `C` means starting from the RISC-V core, and starting with `B` means starting from the ARM core.
+
+- RISC-V:
+  ```
+  C.SCS/0/0.C.SCS/0/0.WD.URPL.USBI.USBW
+  ```
+- ARM:
+  ```
+  B.SCS/0/0.WD.URPL.B.SCS/0/0.WD.URPL.USBI.USBW
+  ```

i18n/zh/docusaurus-plugin-content-docs/current/duo/getting-started/duo256m.md

@@ -25,7 +25,7 @@ Milk-V 是 SG2002 芯片的全球授权经销商。您可以直接从我们的
 
 ## Duo256M GPIO 引脚分配
 
-<Image src='/docs/duo/duo/duo-pinout-01.webp' maxWidth='50%' align='center' />
+<Image src='/docs/duo/duo256m/duo256m-pinout-01.webp' maxWidth='50%' align='center' />
 
 ### GPIO 引脚映射
 
@@ -73,3 +73,22 @@ Milk-V 是 SG2002 芯片的全球授权经销商。您可以直接从我们的
 </div>
 
 GP26 和 GP27 引脚逻辑电平为 1.8V, 其他 GPIO 逻辑电平均为 3.3V 逻辑电平。
+
+## Duo256M 使用指引
+
+### RISC-V 与 ARM 切换
+
+Duo256M 的大核可以选择使用 RISC-V 或者 ARM，默认使用的是 RISC-V 核，可以通过短接物理引脚 35（Boot-Switch）和 GND 来切换到 ARM 核。如果您在使用中发现 Duo256M 不能正常启动，请先检查当前使用的核与使用的固件是否一致。
+
+<Image src='/docs/duo/duo256m/duo256m-arm-riscv-switch.webp' maxWidth='50%' align='center' />
+
+如果连接了调试串口，可以在第一行开机日志中看到，以 `C` 开头时代表从 RISC-V 核启动，以 `B` 开头时代表从 ARM 核启动。
+
+- RISC-V:
+  ```
+  C.SCS/0/0.C.SCS/0/0.WD.URPL.USBI.USBW
+  ```
+- ARM:
+  ```
+  B.SCS/0/0.WD.URPL.B.SCS/0/0.WD.URPL.USBI.USBW
+  ```