Update docs/configuring-playbook-bridge-appservice-slack.md: adopt the common expression for troubleshooting

Signed-off-by: Suguru Hirahara <acioustick@noreply.codeberg.org>

docs/configuring-playbook-bridge-appservice-slack.md

@@ -135,7 +135,7 @@ Unlinking doesn't only disconnect the bridge, but also makes the slackbot leave
 
 ## Troubleshooting
 
-As always, check the logs: `journalctl -fu matrix-appservice-slack`
+As with all other services, you can find the logs in [systemd-journald](https://www.freedesktop.org/software/systemd/man/systemd-journald.service.html) by logging in to the server with SSH and running `journalctl -fu matrix-appservice-slack`.
 
 ### Linking: "Room is now pending-name"