Use rfc-editor.org domain for RFCs (#188)

* Use rfc-editor.org domain for RFCs

* Update with suggestion from @cmb69

Author: Girgias

entities/global.ent

@@ -403,7 +403,7 @@
 <!ENTITY url.rec-xml "http://www.w3.org/TR/1998/REC-xml-19980210">
 <!ENTITY url.relaxng "http://www.relaxng.org/">
 <!-- linking to specific rfcs is done like so: &url.rfc;xxxx so for example &url.rfc;2042 -->
-<!ENTITY url.rfc  'http://www.faqs.org/rfcs/rfc'>
+<!ENTITY url.rfc "https://datatracker.ietf.org/doc/html/rfc">
 <!ENTITY url.rnp "https://www.rnpgp.org/">
 <!ENTITY url.iana.system-names 'http://www.iana.org/assignments/operating-system-names'>
 <!ENTITY url.rpmfind "http://www.rpmfind.net/">