Expand on direnv section

The direnv section simply refers the reader to direnv.net for Linux installation instructions (by the the site is not linked on the page). Since there are different ways to get direnv working depending on if you're using pyenv, virtualenv, or virtualenvwrapper, it seems reasonable to direct them to the site. However, after struggling with this myself I found the instructions not straightforward, especially for a new user.
Since the direnv section directly follows the virtualenvwrapper section, I suggest updating with the following instructions to get direnv working with virtualenvwrapper:

1. Add the following to ~/.config/direnv/direnvrc

layout_virtualenv {
    local venv_path="$1"
    source ${venv_path}/bin/activate
}
layout_virtualenvwrapper {
    local venv_path="${WORKON_HOME}/$1"
    layout_virtualenv $venv_path
}

2. Add the following to an .envrc file in the root directory of your project
   layout virtualenvwrapper _name_of_virtual_environment_

Now, the virtual environment will activate when you enter the project directory and deactivate when you leave.

找出緊接在 virtualenvwrapper 區段之後的 direnv 區段，並檢查周圍的文件如何連結到外部安裝指南。加入 direnv.net 連結和提供的 virtualenvwrapper 設定步驟，然後確認轉譯後的指南是否清楚說明進入和離開專案目錄時的啟用方式。