Update the TensorRT backend docs page

The TensorRT backend page had drifted away from Torch-TensorRT, the project
that builds and ships the TensorRT delegate. It pointed readers at a nightly
build from early October. It said that CUDA graph replay never runs for
engines on the shared activation scratch, which nightly builds now do. It
repeated most of the Torch-TensorRT deployment guide, so every change to the
delegate had to be made in two places. The backends table listed TensorRT as
Linux only.

The page keeps the usual backend sections but says less in each and shows
more code: the one-line install command, export, sending unsupported
operators to the CUDA backend, keeping inputs and outputs on the GPU, Python
and C++ runtime integration (a main.cpp, a complete CMakeLists.txt, and the
build and run commands), and a short list of performance options that link to
the Torch-TensorRT guide. It describes Torch-TensorRT 2.15 and newer and marks
the two features that need a newer build. The examples no longer pass
retrace=False, because save keeps the compiled graph by default.

Author: shoumikhin

docs/source/backends-overview.md

@@ -22,7 +22,7 @@ Backends are the bridge between your exported model and the hardware it runs on.
 |--------------------------------------------------------------|---------------|---------------|---------------------------------|
 | [XNNPACK](backends/xnnpack/xnnpack-overview.md)              | All           | CPU           | General-purpose, fallback       |
 | [CUDA](backends/cuda/cuda-overview.md)                       | Linux/Windows | GPU           | NVIDIA GPU acceleration         |
-| [TensorRT](backends/tensorrt/tensorrt-overview.md)           | Linux         | GPU           | NVIDIA GPU acceleration via TensorRT |
+| [TensorRT](backends/tensorrt/tensorrt-overview.md)           | Linux/Windows | GPU           | NVIDIA GPU acceleration via TensorRT |
 | [Core ML](backends/coreml/coreml-overview.md)                | iOS, macOS    | NPU/GPU/CPU   | Apple devices, high performance |
 | [MLX](/backends/mlx/mlx-overview.md)                         | iOS (experimental), macOS | GPU | Apple Silicon GPU (MLX)         |
 | [Vulkan](backends/vulkan/vulkan-overview.md)                 | Android, Linux, Windows | GPU  | Android devices (mature); Desktops (experimental) |