Add config samples to federated editing docs

Signed-off-by: Julius Härtl <jus@bitgrid.net>

docs/federated-editing.md

@@ -6,7 +6,23 @@ connect to that through their Nextcloud instance (Initiator).
 
 In a federated scenario both Nextcloud servers need to add each other as trusted servers or in a
 global scale environment a list of nodes can be added through the `gs.trustedHosts` setting in the
-config.php file.
+config.php file:
+
+```php
+'gs.trustedHosts' => [
+	'gs1.example.com',
+	'gs2.example.com',
+	'collabora.example.com'
+]
+```
+
+Using wildcards is also possible:
+
+```php
+'gs.trustedHosts' => [
+	'*.example.com'
+]
+```
 
 When a Initiator opens a file that is located on an incoming federated share, a check will be
 performed if the share owners instance supports federated editing. If that is the case a Initiator
@@ -14,3 +30,10 @@ token will be created, and the user will be redirected to the Source instance to
 
 The source instance will then fetch the user and file details, create a WOPI token for the remote
 user with those details and open the document with that.
+
+## Allow remote access on Collabora
+Collabora by default only allows embedding from the same remote that the initial frame is loaded. In order to enable embedding also in trusted remotes like a different GS node, the following setting will allow that:
+
+Assuming gs1.example.com and gs2.example.com are Nextcloud servers:
+
+	coolconfig set net.frame_ancestors "*.example.com"