termux-vibrate: Fix help text for --duration

diff --git a/packages/termux-api/termux-vibrate b/packages/termux-api/termux-vibrate
index 4c51093..36fd2f9 100755 (executable)
--- a/packages/termux-api/termux-vibrate
+++ b/packages/termux-api/termux-vibrate
@@ -3,8 +3,9 @@
 set -e -u
 
 show_usage () {
-       echo 'usage: termux-vibrate [-f,--force] [<duration_ms>]'
+       echo 'usage: termux-vibrate [-f,--force] [-d,--duration <duration_ms>]'
        echo 'Vibrate the device for the specified duration (default:1000 ms).'
+       echo ''
        echo 'By default no vibration is done when in silent mode - use the'
        echo '-f,--force option to force vibration even when in silent mode.'
        exit 1