EGL Headless

The graphics configuration shown in the tutorial doesn't work for me on an RTX 3060:

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Adding an explicit `rendernode` pointing to the correct DRI device fixed it:

```

```

Might be worth updating the tutorial to mention that the render node sometimes needs to be set explicitly, since it's not auto-detected correctly on all setups (RTX 3060 in my case).

Locate the tutorial section showing the EGL headless graphics configuration and review the existing example. Update it to mention that automatic render-node detection may fail on some setups, using the explicit /dev/dri/renderD128 example from the issue. Done means the tutorial explains when rendernode may need to be set manually.

Written by the indexing model from the issue text.