Update Vulkan backend docs

Author: Reubend

docs/source/backends-overview.md

@@ -24,7 +24,7 @@ Backends are the bridge between your exported model and the hardware it runs on.
 | [CUDA](backends/cuda/cuda-overview.md)                       | Linux/Windows | GPU           | NVIDIA GPU acceleration         |
 | [Core ML](backends/coreml/coreml-overview.md)                | iOS, macOS    | NPU/GPU/CPU   | Apple devices, high performance |
 | [Metal Performance Shaders](backends/mps/mps-overview.md)    | iOS, macOS    | GPU           | Apple GPU acceleration          |
-| [Vulkan](backends/vulkan/vulkan-overview.md)                 | Android       | GPU           | Android GPU acceleration        |
+| [Vulkan](backends/vulkan/vulkan-overview.md)                 | Android, Linux, Windows | GPU  | Android devices (mature); Desktops (experimental) |
 | [Qualcomm](backends-qualcomm)                                | Android     | NPU           | Qualcomm SoCs                   |
 | [MediaTek](backends-mediatek)                                | Android     | NPU           | MediaTek SoCs                   |
 | [Arm Ethos-U](backends/arm-ethos-u/arm-ethos-u-overview.md)  | Embedded    | NPU           | Arm MCUs                        |

docs/source/backends/vulkan/vulkan-overview.md

@@ -3,7 +3,8 @@
 The ExecuTorch Vulkan (ET-VK) backend enables ExecuTorch models to execute on
 GPUs via the cross-platform [Vulkan API](https://www.vulkan.org/). Although the
 Vulkan API support is almost ubiquitous among modern GPUs, the ExecuTorch Vulkan
-backend is currently developed with a specific focus for **Android GPUs**.
+backend is developed with a focus on **Android GPUs**, and support for desktop
+platforms is experimental.
 
 ## Features