Replace HTTP links with HTTPS ones: X.25 network layer

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 both the HTTP and HTTPS versions
          return 200 OK and serve the same content:
            Replace HTTP with HTTPS.
Signed-off-by: NAlexander A. Klimov <grandmaster@al2klimov.de>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/x25/Kconfig

@@ -17,7 +17,7 @@ config X25
 	  if you want that) and the lower level data link layer protocol LAPB
 	  (say Y to "LAPB Data Link Driver" below if you want that).
 
-	  You can read more about X.25 at <http://www.sangoma.com/tutorials/x25/> and
+	  You can read more about X.25 at <https://www.sangoma.com/tutorials/x25/> and
 	  <http://docwiki.cisco.com/wiki/X.25>.
 	  Information about X.25 for Linux is contained in the files
 	  <file:Documentation/networking/x25.rst> and