Update matterbridge.md

Not actually tested, but it should be mostly correct.

support/documentation/content/en/documentation/admin/advanced/matterbridge.md

@@ -5,4 +5,61 @@ weight: 50
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-Here is a tutorial to use Matterbridge with the plugin: <https://gitlab.com/refrac/obs-matterbridge-overlay/-/blob/master/documentation/peertube.md>
+The following is based on a tutorial to use Matterbridge with the plugin: <https://gitlab.com/refrac/obs-matterbridge-overlay/-/blob/master/documentation/peertube.md>
+
+## Requirements
+- [PeerTube plugin livechat](https://github.com/JohnXLivingston/peertube-plugin-livechat) version 3.2.0 or later.
+- [Matterbridge](https://github.com/42wim/matterbridge) version 1.22.4 or later.
+
+The easiest is if the PeerTube instance and Matterbridge run on the same machine.
+
+## Internal connections only (basic)
+You will need to enable the new advanced option added in 3.2.0 for built-in Prosody: **`Enable client to server connections`**.
+
+This will allow localhost XMPP clients to connect to the Prosody server.
+
+You may need to add some line to your `/etc/hosts`:
+
+```
+127.0.0.1       anon.example.org room.example.org
+```
+Replace `example.org` by your actual instance domain name. Afterwards you can continue with the Matterbridge configuration below.
+
+## Allow external connections (advanced)
+
+By default, the internal Prosody server only listens on localhost (127.0.0.1). 
+
+On versions later than 10.0.2 a new option call `Client to server network interfaces` was added to allow changing this.
+
+It allows to add a list of IPs to listen on, coma separated (spaces will be stripped). 
+
+You can also use `*` to listen on all IPv4 interfaces, and `::` for all IPv6. Doing so allows external access to the client to server interface.
+
+Then you need to open and forward the C2S port (by default `5222`) in your firewall so that it can be reached from the internet.
+
+And you need to add DNS records for `anon.example.org` and `room.example.org` to your domain. 
+
+In case you are using a port other than `5222` you also need to set the [xmpp-client SRV record](https://prosody.im/doc/dns#srv_records) to the correct port.
+
+## Configurating Matterbridge
+
+In the version 1.22.4, Matterbridge added support for XMPP anonymous connections needed to connect to the built-in prosody.
+
+So in the TOML config file put:
+
+``` TOML
+[xmpp.mypeertube]
+Anonymous=true
+Server="anon.example.org:5222"
+Muc="room.example.org"
+Nick="Matterbridge"
+RemoteNickFormat="[{PROTOCOL}] <{NICK}> "
+NoTLS=true
+```
+- Replace `example.org` by your actual instance domain name.
+- Replace `5222` by the actual port if you changed it.
+- `mypeertube` can be replaced by another name.
+- Using `peertube` as the Nick will provide put PeerTube icon for overlay messages, can be also done with overlay config modification.
+- The setting `NoTLS=true` allows connecting to a server with self-signed certificates.
+
+Now you can add this account to gateways and bridge specific live-chat channels.