Prosody: new settings to provide a custom certificates dir

languages/settings/en.yml

@@ -170,6 +170,12 @@ prosody_s2s_interfaces_description: |
     <li>172.18.0.42</li>
   </ul>
 
+prosody_certificates_dir_label: "Certificates directory"
+prosody_certificates_dir_description: |
+  If this field is empty, the plugin will generate and use self-signed certificates.<br>
+  If you want to use other certificates, just specify here the folder where
+  Prosody can find them. Note: the `peertube` user must have read access to this directory.
+
 prosody_c2s_label: "Enable client to server connections"
 prosody_c2s_description: |
   Enable XMPP clients to connect to the built-in Prosody server.<br>