Documentation/isdn: check and fix dead links ...

and switch to https where possible.

All links have been eyeballed to verify that the domains have
not changed, etc.

Signed-off-by: Sanjeev Gupta <ghane0@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/Documentation/isdn/README.FAQ b/Documentation/isdn/README.FAQ
index 356f794..e5dd1ad 100644
--- a/Documentation/isdn/README.FAQ
+++ b/Documentation/isdn/README.FAQ
@@ -8,9 +8,9 @@
 
 In case you just want to see the FAQ online, or download the newest version,
 you can have a look at my website:
-http://www.mhessler.de/i4lfaq/ (view + download)
+https://www.mhessler.de/i4lfaq/ (view + download)
 or:
-http://www.isdn4linux.de/faq/ (view)
+https://www.isdn4linux.de/faq/4lfaq.html (view)
 
 As the extension tells, the FAQ is in SGML format, and you can convert it
 into text/html/... format by using the sgml2txt/sgml2html/... tools.