readme : add Vulkan notice (#2488)

* Add Vulkan notice in README.md

* Fix formatting for Vulkan section in README.md

* Fix formatting in README.md

Author: toboil-features

README.md

@@ -18,6 +18,7 @@ High-performance inference of [OpenAI's Whisper](https://github.com/openai/whisp
 - Mixed F16 / F32 precision
 - [4-bit and 5-bit integer quantization support](https://github.com/ggerganov/whisper.cpp#quantization)
 - Zero memory allocations at runtime
+- Vulkan support
 - Support for CPU-only inference
 - [Efficient GPU support for NVIDIA](https://github.com/ggerganov/whisper.cpp#nvidia-gpu-support-via-cublas)
 - [OpenVINO Support](https://github.com/ggerganov/whisper.cpp#openvino-support)
@@ -429,6 +430,16 @@ make clean
 GGML_CUDA=1 make -j
 ```
 
+## Vulkan GPU support
+Cross-vendor solution which allows you to accelerate workload on your GPU.
+First, make sure your graphics card driver provides support for Vulkan API.
+
+Now build `whisper.cpp` with Vulkan support:
+```
+make clean
+make GGML_VULKAN=1
+```
+
 ## BLAS CPU support via OpenBLAS
 
 Encoder processing can be accelerated on the CPU via OpenBLAS.