Adjust the URL in the README.rst file to point to LiberaChat instead of freenode (#10258)

README.rst

@@ -25,7 +25,7 @@ The overall architecture is::
 
 ``#matrix:matrix.org`` is the official support room for Matrix, and can be
 accessed by any client from https://matrix.org/docs/projects/try-matrix-now.html or
-via IRC bridge at irc://irc.freenode.net/matrix.
+via IRC bridge at irc://irc.libera.chat/matrix.
 
 Synapse is currently in rapid development, but as of version 0.5 we believe it
 is sufficiently stable to be run as an internet-facing service for real usage!

changelog.d/10258.doc

@@ -0,0 +1 @@
+Adjust the URL in the README.rst file to point to irc.libera.chat.