[doc] update how pip can install nightly wheels (vllm-project#11806)

Signed-off-by: youkaichao <[email protected]>

Author: youkaichao

docs/source/getting_started/installation/gpu-cuda.md

@@ -66,19 +66,19 @@ LLM inference is a fast-evolving field, and the latest code may contain bug fixe
 ### Install the latest code using `pip`
 
 ```console
-$ pip install https://vllm-wheels.s3.us-west-2.amazonaws.com/nightly/vllm-1.0.0.dev-cp38-abi3-manylinux1_x86_64.whl
+$ pip install vllm --pre --extra-index-url https://wheels.vllm.ai/nightly
 ```
 
-If you want to access the wheels for previous commits (e.g. to bisect the behavior change, performance regression), you can specify the commit hash in the URL:
+`--pre` is required for `pip` to consider pre-released versions.
+
+If you want to access the wheels for previous commits (e.g. to bisect the behavior change, performance regression), due to the limitation of `pip`, you have to specify the full URL of the wheel file by embedding the commit hash in the URL:
 
 ```console
 $ export VLLM_COMMIT=33f460b17a54acb3b6cc0b03f4a17876cff5eafd # use full commit hash from the main branch
 $ pip install https://vllm-wheels.s3.us-west-2.amazonaws.com/${VLLM_COMMIT}/vllm-1.0.0.dev-cp38-abi3-manylinux1_x86_64.whl
 ```
 
-Note that the wheels are built with Python 3.8 ABI (see [PEP 425](https://peps.python.org/pep-0425/) for more details about ABI), so **they are compatible with Python 3.8 and later**. The version string in the wheel file name (`1.0.0.dev`) is just a placeholder to have a unified URL for the wheels. The actual versions of wheels are contained in the wheel metadata. Although we don't support Python 3.8 any more (because PyTorch 2.5 dropped support for Python 3.8), the wheels are still built with Python 3.8 ABI to keep the same wheel name as before.
-
-Due to the limitation of `pip`, you have to specify the full URL of the wheel file.
+Note that the wheels are built with Python 3.8 ABI (see [PEP 425](https://peps.python.org/pep-0425/) for more details about ABI), so **they are compatible with Python 3.8 and later**. The version string in the wheel file name (`1.0.0.dev`) is just a placeholder to have a unified URL for the wheels, the actual versions of wheels are contained in the wheel metadata (the wheels listed in the extra index url have correct versions). Although we don't support Python 3.8 any more (because PyTorch 2.5 dropped support for Python 3.8), the wheels are still built with Python 3.8 ABI to keep the same wheel name as before.
 
 ### Install the latest code using `uv`
 
@@ -126,7 +126,7 @@ $ cd vllm
 $ VLLM_USE_PRECOMPILED=1 pip install --editable .
 ```
 
-This will download the latest nightly wheel and use the compiled libraries from there in the install.
+This will download the latest nightly wheel from https://vllm-wheels.s3.us-west-2.amazonaws.com/nightly/vllm-1.0.0.dev-cp38-abi3-manylinux1_x86_64.whl and use the compiled libraries from there in the installation.
 
 The `VLLM_PRECOMPILED_WHEEL_LOCATION` environment variable can be used instead of `VLLM_USE_PRECOMPILED` to specify a custom path or URL to the wheel file. For example, to use the [0.6.1.post1 PyPi wheel](https://pypi.org/project/vllm/#files):