from pathlib import Path


def render_doxygen_mainpage() -> str:
    """Render the mainpage.dox page that provides content for the Doxygen
    subsite's homepage.

    Returns
    -------
    content : `str`
        The content of ``mainpage.dox``.
    """
    template_path = Path(__file__).parent / "data" / "mainpage.dox"
    template = template_path.read_text()
    return template