Add matrix documentation

index.rst

@@ -79,6 +79,7 @@ NethServer 8 administrator manual
    webserver
    sogo
    odoo
+   matrix
 
 .. toctree::
    :maxdepth: 2

matrix.rst

@@ -0,0 +1,26 @@
+.. _matrix-section:
+
+======
+Matrix
+======
+
+Matrix is an open network for secure, decentralised communication. This implementation provides a complete chat solution, 
+including the synapse homeserver and web clients like Element web or Cinny.
+Please see the `official website <https://www.matrix.org>`_.
+
+Configuration
+=============
+
+Synapse, Element web and Cinny need a dedicated virtual host, a FQDN like ``fqdn.nethserver.org``.
+
+Before proceeding with the configuration, make sure to create the corresponding name records inside your DNS server.
+If you are planning to use a Let's Encrypt certificate as default, make also sure to have a corresponding public DNS record.
+
+How to configure:
+
+1. access the ``Settings`` page of the newly installed instance
+2. enter a valid FQDN inside the ``Matrix server domain`` field
+3. to start the web clients, you need to enter a valid FQDN inside the ``Element web domain`` or the ``Cinny domain`` fields.
+4. enable ``Let's Encrypt`` and ``HTTP to HTTPS`` options accordingly to your needs
+5. select a ``Timezone``
+6. click the :guilabel:`Save` button