S390: Replace HTTP links with HTTPS ones

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:
  If not .svg:
    For each line:
      If doesn't contain `\bxmlns\b`:
        For each link, `\bhttp://[^# \t\r\n]*(?:\w|/)`:
	  If neither `\bgnu\.org/license`, nor `\bmozilla\.org/MPL\b`:
            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>
Link: https://lore.kernel.org/r/20200709182742.24724-1-grandmaster@al2klimov.deSigned-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/s390/monreader.rst

@@ -146,7 +146,7 @@ start offset relative to a 4K page (frame) boundary.
 
 See "Appendix A: `*MONITOR`" in the "z/VM Performance" document for a description
 of the monitor control element layout. The layout of the monitor records can
-be found here (z/VM 5.1): http://www.vm.ibm.com/pubs/mon510/index.html
+be found here (z/VM 5.1): https://www.vm.ibm.com/pubs/mon510/index.html
 
 The layout of the data stream provided by the monreader device is as follows::