Return split readme.

def split_readme(readme_path, before_key, after_key, options_key, end_key):
    """Return split readme."""
    with open(readme_path) as readme_file:
        readme = readme_file.read()

    top, rest = readme.split(before_key)
    before, rest = rest.split(after_key)
    _, rest = rest.split(options_key)
    _, bottom = rest.split(end_key)

    return (top.rstrip('\n'),
            before.strip('\n'),
            end_key + '\n\n' + bottom.lstrip('\n'))