Add instructions to disable admin password

Since RPi OS version 6.2, the admin password is required by default for all sudo commands. The added instructions explain how to disable it for the software to function correctly.

Author: maxsitt

docs/software/pisetup.md

@@ -18,8 +18,9 @@ Select your SD card as storage medium and continue to the **Customisation** sett
   you will need it to connect to the RPi via SSH later.
 - Check if the **Localisation** settings are already correct and modify them if needed.
 - Continue to **User** and keep the default `pi` as username. Changing the username will
-  break the software functionality, do this on your own risk. Choose a simple password, you
-  won't actually need it, as we will set up SSH key based authentication in the next steps.
+  break the software functionality, do this on your own risk. Choose a password and note
+  it. By default, you will need it when running `sudo` commands since RPi OS version 6.2.
+  Make sure to change this default setting in the [Update RPi](#update-rpi) step.
 
     ![Raspberry Pi Imager Choose Username](assets/images/raspberrypi_imager_choose_username.png){ width="700" }
 
@@ -175,6 +176,25 @@ folder in VS Code. This makes working with files on the Raspberry Pi easier
 
 ## Update RPi
 
+!!! warning "Disable admin password"
+
+    If you set up your SD card after April 14 (2026), you will have the latest
+    RPi OS 6.2 installed, where passwordless sudo is now disabled by default
+    ([blog post](https://www.raspberrypi.com/news/a-security-update-for-raspberry-pi-os/){target=_blank}).
+    For the insect-detect software to function correctly, we will need to enable
+    passwordless sudo again by disabling the admin password in the system settings.
+
+    Open the [`raspi-config`](https://www.raspberrypi.com/documentation/computers/configuration.html#raspi-config){target=_blank}
+    tool by running:
+
+    ``` bash
+    sudo raspi-config
+    ```
+
+    Go to `1 System Options` and then `S10 Admin Password`. When asked if you would
+    like the admin (sudo) password to be enabled, choose `No`, which will disable the
+    admin password. Hit `Finish` to close the `raspi-config` tool.
+
 We will start with updating the already installed software by running:
 
 ``` bash