Feature: Document SELinux bind-mount note for local devcontainer usage

Describe the enhancement or feature you would like

When using the CPython devcontainer image on SELinux-enabled Linux hosts, a plain bind mount may fail with Permission denied inside the container.

Example:

docker run -it --rm \
  -v "$PWD:/workspace" \
  -w /workspace \
  ghcr.io/python/devcontainer:latest

In that case, a SELinux-compatible bind mount works:

  docker run -it --rm \
  -v "$PWD:/workspace:Z" \
  -w /workspace \
  ghcr.io/python/devcontainer:latest

Without relabeling, /workspace may not be readable from inside the container.

It may be helpful to add a short note to the local Docker/devcontainer documentation for SELinux-enabled hosts, preferably using the :Z bind-mount form.

Describe alternatives you have considered

As an alternative workaround, this also works:

docker run -it --rm \
  --security-opt label=disable \
  -v "$PWD:/workspace" \
  -w /workspace \
  ghcr.io/python/devcontainer:latest

Additional context

No response

在本地 Docker/devcontainer 文件中查找 issue 所示的 bind-mount 用法。為啟用 SELinux 的 Linux 主機新增一則簡短說明，使用 :Z 形式的 bind-mount，並在適當情況下提及停用標籤的替代做法。完成的標準是文件說明一般 mount 為何可能失敗，並展示一個可運作的命令。