Update pullio info

Put in a test command for pullio.

docs/Hardlinks/How-to-setup-for/Synology.md

@@ -271,6 +271,10 @@ At `Task Settings` tab, add the following line in the Run Command section:
    /usr/local/bin/pullio > /volume1/docker/appdata/pullio/pullio.log 2>&1
 ```
 
+To test if Pullio works, run this command in your terminal: `sudo pullio --debug`.
+
+You should see that it will download and recreate all the containers and also get notifications (if you have this enabled).
+
 More info about Pullio [HERE](https://hotio.dev/pullio/){:target="_blank" rel="noopener noreferrer"}
 
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