[misc] add instructions on how to install nvshmem/pplx/deepep (#17964)

Signed-off-by: youkaichao <youkaichao@gmail.com>

tools/ep_kernels/README.md

@@ -0,0 +1,27 @@
+Large-scale cluster-level expert parallel, as described in the [DeepSeek-V3 Technical Report](http://arxiv.org/abs/2412.19437), is an efficient way to deploy sparse MoE models with many experts. However, such deployment requires many components beyond a normal Python package, including system package support and system driver support. It is impossible to bundle all these components into a Python package.
+
+Here we break down the requirements in 3 steps:
+1. Build and install the Python libraries (both [pplx-kernels](https://github.com/ppl-ai/pplx-kernels) and [DeepEP](https://github.com/deepseek-ai/DeepEP)), including necessary dependencies like NVSHMEM. This step does not require any privileged access. Any user can do this.
+2. Build and install the system libraries (GDR Copy). This step requires root access. You can do it inside a Docker container so that they can be shipped as a single image.
+3. Build and install the system drivers (GDR Copy, and necessary modifications to NVIDIA driver to enable IBGDA). This step requires root access, and must be done on the host machine.
+
+2 and 3 are necessary for multi-node deployment.
+
+All scripts accept a positional argument as workspace path for staging the build, defaulting to `$(pwd)/ep_kernels_workspace`.
+
+# Usage
+
+## Single-node
+
+```bash
+bash install_python_libraries.sh
+```
+
+## Multi-node
+
+```bash
+bash install_python_libraries.sh
+sudo bash install_system_libraries.sh
+sudo bash install_system_drivers.sh
+sudo reboot # Reboot is required to load the new driver
+```