docs: add missing arguments

* add a missing argument --no--restart
* add a missing env variable name for argument --debug

docs/arguments.md

@@ -62,7 +62,7 @@ Enable debug mode with verbose logging.
 
 ```
             Argument: --debug
-Environment Variable: N/A
+Environment Variable: WATCHTOWER_DEBUG
                 Type: Boolean
              Default: false
 ```
@@ -127,6 +127,16 @@ Environment Variable: WATCHTOWER_MONITOR_ONLY
              Default: false
 ``` 
 
+## Without restarting containers
+Do not restart containers after updating. This option can be useful when the start of the containers
+is managed by an external system such as systemd.
+```
+            Argument: --no-restart
+Environment Variable: WATCHTOWER_NO_RESTART
+                Type: Boolean
+             Default: false
+```
+
 ## Without pulling new images
 Do not pull new images. When this flag is specified, watchtower will not attempt to pull
 new images from the registry. Instead it will only monitor the local image cache for changes.