general: Fix broken links.

This fixes a number of broken links throughout the
tree, mostly caused by wiki.asterisk.org being replaced
with docs.asterisk.org, which should eliminate the
need for sporadic fixes as in f28047db36.

Resolves: #430

doc/CODING-GUIDELINES

@@ -1,2 +1,2 @@
 Coding guidelines are available on the Asterisk wiki at:
-https://wiki.asterisk.org/wiki/display/AST/Coding+Guidelines
+https://docs.asterisk.org/Development/Policies-and-Procedures/Coding-Guidelines/

doc/README.txt

@@ -1,13 +1,7 @@
 The vast majority of the Asterisk project documentation has been moved to the
-project wiki:
+project documentation:
 
-    https://wiki.asterisk.org/
-
-Asterisk release tarballs contain an export of the wiki in PDF and plain text
-form, which you can find in:
-
-    doc/AST.pdf
-    doc/AST.txt
+    https://docs.asterisk.org/
 
 Asterisk uses the Doxygen documentation software.  Run "make progdocs" and open
 the resulting documentation index at doc/api/index.html in a webbrowser or copy

doc/asterisk.8

@@ -248,7 +248,7 @@ https://www.asterisk.org - The Asterisk Home Page
 .PP
 http://www.asteriskdocs.org - The Asterisk Documentation Project
 .PP
-https://wiki.asterisk.org - The Asterisk Wiki
+https://docs.asterisk.org - The Asterisk documentation
 .PP
 https://www.digium.com/ - Asterisk is sponsored by Digium
 .SH AUTHOR

doc/asterisk.sgml

@@ -427,7 +427,7 @@
    http://www.asteriskdocs.org - The Asterisk Documentation Project
   </para>
   <para>
-   https://wiki.asterisk.org - The Asterisk Wiki
+   https://docs.asterisk.org/ - The Asterisk documentation
   </para>
   <para>
    https://www.digium.com/ - Asterisk is sponsored by Digium

doc/lang/language-criteria.txt

@@ -1,3 +1,3 @@
 This document has been moved to the Asterisk Wiki:
 
-https://wiki.asterisk.org/wiki/display/AST/Asterisk+Sounds+Submission+Process
+https://docs.asterisk.org/Development/Policies-and-Procedures/Asterisk-Sounds-Submission-Process/