🔨Add proxy_host/app_url variable

fixes #12

Author: sinclairpaul

bookstack/config.json

@@ -29,6 +29,7 @@
     "remote_mysql_username": "str?",
     "remote_mysql_password": "password?",
     "remote_mysql_port": "int?",
+    "proxy_host": "str?",
     "log_level": "list(trace|debug|info|notice|warning|error|fatal)?",
     "certfile": "str",
     "keyfile": "str",

bookstack/rootfs/etc/services.d/php-fpm/run

@@ -4,6 +4,7 @@
 # Runs the PHP-FPM daemon
 # ==============================================================================
 export APP_KEY
+export APP_URL
 export DB_DATABASE
 export DB_HOST
 export DB_PASSWORD
@@ -26,6 +27,10 @@ else
     DB_PORT=$(bashio::services "mysql" "port")
 fi
 
+if bashio::config.has_value 'proxy_host';then
+    APP_URL=$(bashio::config "proxy_host")
+fi
+
 bashio::log.info "Installing/updating Database"
 php /var/www/bookstack/artisan migrate --force