matrix.md: added irc bridge section

content/eng/matrix.md

@@ -23,7 +23,7 @@ We have an instance of maubot which runs the following:
 
 ## XMPP Bridge
 
-We also host bifrost, a XMPP bridge.
+We host bifrost, a XMPP bridge.
 
 The address syntax to access XMPP from Matrix:
 
@@ -43,6 +43,43 @@ It also supports plumbing of existent Matrix rooms to XMPP rooms, room administr
 
 You can also type `!bifrost help` for help on bifrost commands at any time.
 
+## IRC Bridge
+
+We host relixbox, an IRC bridge.
+
+It is setup in the backend, however. The configuration is the Python script itself. This means that if you want to bridge your rooms, you need to run the script in your pubnix account.
+
+Firstly, clone it from [the git upstream](https://git.vitali64.duckdns.org/misc/relixbot.git) [(tor alternative link)](http://fs4xhnfag3udez4qhfpyxdvnue7aebrw2kbc2tcvnbrsecxlpcscgxyd.onion/misc/relixbot.git). Then, you can edit the following variables:
+
+```python
+server          = [ ['irc.libera.chat', 'libera'], ['mtrx.vern.cc', 'matrix'] ]
+# Use the internal matrix room address.
+relayedChannels = [ [ '#chan1', '!aBCrdDeRfG:matrix.org' ], [ '##chan2', '!xgwAUWHbwWUG:vern.cc' ] ]
+nick            = 'TestRelay'
+debug           = True
+channels        = [ 0, 1 ] # Multiple channels
+join_leave_msgs = False # Relay Join/Left messages.
+```
+
+They should be self-explanatory, apart from the `channels` variable, that should contain the indexes of how many channels you are bridging. For example, if you have `relayedChannels = [ ["#chan1", "!idk:matrix.org"] ]` set, it should contain `[ 0 ]`. If you have `relayedChannels = [ [ '#chan1', '!aBCrdDeRfG:matrix.org' ], [ '##chan2', '!xgwAUWHbwWUG:vern.cc' ], [ '#chan3', '!edwfsiofn:vern.cc' ] ]`, it should contain `[ 0, 1, 2 ]` and so on.
+
+After editing the configuration to your liking, you should be able to create a SystemD user unit, following this example:
+
+```ini
+[Unit]
+Description=IRC to Matrix Bridge
+
+[Service]
+ExecStart=/run/current-system/sw/bin/python3 /home/<your username>/irc-bridge.py
+
+[Install]
+WantedBy=default.target
+```
+
+Write the file to `~/.config/systemd/user/irc-bridge.service`, then enable the service by running `systemctl --user enable --now irc-bridge.service`.
+
+Done! You should have a working IRC bridge hosted at your pubnix account.
+
 ## Message Retention
 
 We currently do not have a message retention policy set, but its possible to delete all your messages when you deactivate your user by setting `erase=true` option in json.