Rationale:
Reduces attack surface on kernel devs opening the links for MITM
as HTTPS traffic is much harder to manipulate.

Deterministic algorithm:
For each file:
  For each line:
    If doesn't contain `\bxmlns\b`:
      For each link, `\bhttp://[^# \t\r\n]*(?:\w|/)`:
        If both the HTTP and HTTPS versions
        return 200 OK and serve the same content:
          Replace HTTP with HTTPS.
Signed-off-by: Alexander A. Klimov <grandmaster@al2klimov.de>
Reviewed-by: Alex Shi <alex.shi@linux.alibaba.com>
Link: https://lore.kernel.org/r/20200608181649.74883-1-grandmaster@al2klimov.deSigned-off-by: Jonathan Corbet <corbet@lwn.net>