Remove mentioning of IRC

* README
  (#PARTICIPATING IN THE SUBVERSION COMMUNITY): As above


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1932863 13f79535-47bb-0310-9956-ffa450edef68

Author: d-sahlberg

README

@@ -49,8 +49,6 @@ III.  PARTICIPATING IN THE SUBVERSION COMMUNITY
       It describes Subversion coding and log message standards, as well
       as how to join discussion lists.
 
-      Talk on IRC with developers:  irc.libera.chat, channel #svn-dev.
-
       Read the FAQ:  https://subversion.apache.org/faq.html