README: Remove outdated references to tex docs

Added links to the wiki to replace references to outdated
tex docs.

ASTERISK-27430
Reported by: Corey Farrell

Change-Id: I5007e732b30bc7b63d124c530ae8857c89991209

README-SERIOUSLY.bestpractices.md

@@ -17,7 +17,8 @@ change over time as best practices are defined.
         Recognizing potential issues with certain classes of authorization
 * [Avoid Privilege Escalations]:
         Disable the ability to execute functions that may escalate privileges
-
+* [Important Security Considerations]:
+        More information on the Asterisk Wiki
 
 ## Additional Links
 
@@ -386,3 +387,4 @@ In Asterisk 12 and later, live_dangerously defaults to no.
 [Reducing Pattern Match Typos]: #reducing-pattern-match-typos
 [Manager Class Authorizations]: #manager-class-authorizations
 [Avoid Privilege Escalations]: #avoid-privilege-escalations
+[Important Security Considerations]: https://wiki.asterisk.org/wiki/display/AST/Important+Security+Considerations

README.md

@@ -9,10 +9,7 @@
 the security information document before you attempt to configure and run
 an Asterisk server.
 
-  If you downloaded Asterisk as a tarball, see the security section in the PDF
-version of the documentation in doc/tex/asterisk.pdf.  Alternatively, pull up
-the HTML version of the documentation in doc/tex/asterisk/index.html.  The
-source for the security document is available in doc/tex/security.tex.
+See [Important Security Considerations] for more information.
 
 ## WHAT IS ASTERISK ?
 
@@ -269,4 +266,4 @@ Asterisk is a trademark of Digium, Inc.
 [CHANGES]: CHANGES
 [configs]: configs
 [doc]: doc
-
+[Important Security Considerations]: https://wiki.asterisk.org/wiki/display/AST/Important+Security+Considerations