from typing import List


def fix_headers(contents: str) -> str:
    """Fixes the headers of sections copied from README.

    Removes one octothorpe (#) from all headers since the contents are no longer nested
    in a root document (i.e. the README).
    """
    lines: List[str] = contents.splitlines()
    fixed_contents: List[str] = []
    for line in lines:
        if line.startswith('##'):
            line = line[1:]
        fixed_contents.append(line + '\n')  # splitlines strips the leading newlines
    return ''.join(fixed_contents)