docs: fix canonical link for www.roundup-tracker.org index page the index page canonical link was: https://www...org/index.html change the template so the canonical is set to https://www...org/ as that is how it's listed by crawlers.

try:
    # Python 3+
    from ssl import SSLError
except (ImportError, AttributeError):
    # Python 2.5-2.7
    from socket import sslerror as SSLError  # noqa: F401