Update our docs' references to freenode to libera.chat after move (metabrainz#2117)

Author: reosarevok

INSTALL.md

@@ -445,7 +445,7 @@ If you intend to run a server with translations, there are a few steps to follow
 Troubleshooting
 ---------------
 
-If you have any difficulties, feel free to ask in #metabrainz on irc.freenode.net,
+If you have any difficulties, feel free to ask in #metabrainz on irc.libera.chat,
 or ask on [our forums](https://community.metabrainz.org/c/musicbrainz).
 
 Please report any issues on our [bug tracker](http://tickets.metabrainz.org/).

README.md

@@ -8,7 +8,7 @@ MusicBrainz is a user-maintained open community that collects music metadata
 and makes it available to the public in the form of a relational database.
 For more information, [visit our website](https://musicbrainz.org/doc/About).
 
-To get help, please join #metabrainz on irc.freenode.net
+To get help, please join #metabrainz on irc.libera.chat
 
 Breaking changes to the database schema or our API / web service will be announced on
 [our blog](https://blog.metabrainz.org/category/musicbrainz+breaking-changes/),