add swayidle.sh script

i noticed that after reload, sway doesn't kill previous swayidle,
so i made this script to kill it myself.

Fine, i'll do it myself. As one once said

bin/swayidle.sh

@@ -0,0 +1,7 @@
+#! /bin/bash
+
+killall swayidle
+
+cmd="swaylock"
+
+swayidle before-sleep $cmd