docs: add --no-deps to ROCm install in training.md

[imitater-dou]

Summary

Align the ROCm install snippet in docs/basic_usage/training.md with the other ROCm docs (docs/get_started/installation.md, docs/basic_usage/AMD/amd_rocm.md) by using pip install -e . --no-deps after requirements-rocm.txt.

pyproject.toml pins CUDA-default torch/sglang, so a bare editable install can replace a ROCm stack.

How verified

Verified against upstream sgl-project/SpecForge main SHA 2fc993077c3c53df14ebdd5d414c854864476af8.

Before (docs/basic_usage/training.md ROCm snippet):

python -m pip install -r requirements-rocm.txt
python -m pip install -e .

After:

python -m pip install -r requirements-rocm.txt
python -m pip install -e . --no-deps

Matching --no-deps in other ROCm docs (same SHA):

• docs/get_started/installation.md: python -m pip install -e . --no-deps
• docs/basic_usage/AMD/amd_rocm.md: python -m pip install -e . --no-deps (notes --no-deps is mandatory so CUDA wheels do not clobber ROCm torch/sglang)

pyproject.toml pins (same SHA):

• torch==2.13.0
• sglang==0.5.18