add permalinkPrefix to riot-web config

roles/matrix-riot-web/defaults/main.yml

@@ -29,6 +29,7 @@ matrix_riot_web_integrations_ui_url: "https://scalar.vector.im/"
 matrix_riot_web_integrations_rest_url: "https://scalar.vector.im/api"
 matrix_riot_web_integrations_widgets_urls: ["https://scalar.vector.im/api"]
 matrix_riot_web_integrations_jitsi_widget_url: "https://scalar.vector.im/api/widgets/jitsi.html"
+matrix_riot_web_permalinkPrefix: "https://matrix.to"
 # Riot public room directory server(s)
 matrix_riot_web_roomdir_servers: ['matrix.org']
 matrix_riot_web_welcome_user_id: "@riot-bot:matrix.org"

roles/matrix-riot-web/templates/config.json.j2

@@ -11,6 +11,7 @@
 	"settingDefaults": {
 		"custom_themes": {{ matrix_riot_web_settingDefaults_custom_themes|to_json }}
 	},
+	"permalinkPrefix": {{ matrix_riot_web_permalinkPrefix|string|to_json }},
 	"disable_custom_urls": {{ matrix_riot_web_disable_custom_urls|to_json }},
 	"disable_guests": {{ matrix_riot_web_disable_guests|to_json }},
 	"brand": {{ matrix_riot_web_brand|to_json }},