chore(snippets): add shutdown notes

snippets/shutdown.sh

@@ -0,0 +1,16 @@
+#!/usr/bin/env sh
+
+# Poweroff immediately
+sudo shutdown now
+sudo shutdown -h now
+sudo shutdown -P +0 --no-wall
+
+# Reboot in 1 minutes
+sudo shutdown -r '+15'
+sudo shutdown -r '+15' 'heyo, reboot time!'
+
+# Show pending shutdown actions and time if any
+sudo shutdown --show
+
+# Cancel pending shutdowns
+sudo shutdown -c