Add documentation for forcing OD UI (#2018)

Author: samfreund

docs/source/docs/contributing/building-photon.md

@@ -275,3 +275,9 @@ Using the [GitHub CLI](https://cli.github.com/), we can download artifacts from
 MacOS builds are not published to releases as MacOS is not an officially
 supported platform. However, MacOS builds are still available from the MacOS
 build action, which can be found [here](https://github.com/PhotonVision/photonvision/actions/workflows/build.yml).
+
+#### Forcing Object Detection in the UI
+
+In order to force the Object Detection interface to be visible, it's necessary to hardcode the platform that `Platform.java` returns. This can be done by changing the function that detects the RK3588S/QCS6490 platform to always return true, and changing the `getCurrentPlatform()` function to always return the RK3588S/QCS6490 architecture.
+Alternatively, it's possible to modify the frontend code by changing all instances of `useSettingsStore().general.supportedBackends.length > 0` to `true`, which will force the card to render.
+Make sure to revert these changes before submitting a Pull Request.