Hypr-Ecosystem/hyprsunset: add 'run at startup' section (#979)

Co-authored-by: Mihai Fufezan <mihai@fufexan.net>

pages/Hypr Ecosystem/hyprsunset.md

@@ -27,6 +27,11 @@ below the monitor's minimum.
 
 See `hyprsunset --help`.
 
+## Run at startup
+
+To autostart hyprsunset, add: `exec-once = hyprsunset` to your `hyprland.conf`.
+Alternatively, use `systemctl --user enable --now hyprsunset.service` in order to use hyprsunset as a systemd user service.
+
 ## IPC
 
 `hyprsunset` supports IPC via hyprctl. Both color temperature and the gamma filter are adjustable:
@@ -59,4 +64,4 @@ bindel = ,XF86MonBrightnessUp, exec, hyprctl hyprsunset gamma +10
 
 Using the gamma control will degrade color accuracy. If your monitor does support software control, it is highly recommended to use that instead.
 
-{{< /callout >}}
+{{< /callout >}}