docs: clarify ONNX Runtime dependency and input handling

ONNX Runtime is a configure-time dependency for every build, not only
for the yolo_onnx engine. The event loop no longer inspects the input
id, so it grabs on any input rather than specifically on tick.

scripts/install_linux_arm.sh

@@ -11,8 +11,8 @@
 #   JetPack 7.1     (L4T 38.4)
 #
 # ONNX Runtime: Microsoft does not publish official GPU binaries for ARM64.
-#   The native engine (ZED SDK built-in TensorRT) works without ONNX Runtime.
-#   To use the yolo_onnx engine, build ONNX Runtime from source:
+#   ONNX Runtime is still needed to configure the build; only the yolo_onnx
+#   engine uses it at runtime. Build it from source:
 #   https://onnxruntime.ai/docs/build/eps.html#tensorrt
 set -euo pipefail
 
@@ -66,8 +66,8 @@ fi
 # --- ONNX Runtime ---
 echo ""
 echo ">>> ONNX Runtime (ARM64 GPU): no official pre-built binary available."
-echo "    The native ZED engine works without ONNX Runtime."
-echo "    To use the yolo_onnx engine, build from source:"
+echo "    Needed to configure the build; only yolo_onnx uses it at runtime."
+echo "    Build from source:"
 echo "      https://onnxruntime.ai/docs/build/eps.html#tensorrt"
 echo ""