netbird-install-update: add --help option with usage, options, and examples

netbird-install-update/netbird-install-update.sh

@@ -74,8 +74,47 @@ print_step() {
     echo -e "  ${DIM}•${NC} $1"
 }
 
+print_usage() {
+    cat <<EOF
+Usage: netbird-install-update.sh [options]
+
+Install, update, and manage Netbird across single or multiple Linux hosts.
+
+Options:
+  -h, --help                Show this help message and exit
+  --ssh <host>              Deploy to a single host via SSH
+  --hosts-file, --file <f>  Deploy to multiple hosts from a file
+  --timer                   Install a systemd auto-update timer
+  --time <schedule>         Timer schedule (systemd OnCalendar format, default: daily)
+  -p, --password <pass>     Sudo password for remote hosts (used with --ssh or --hosts-file)
+
+Hosts file format (one per line):
+  hostname_or_ip [sudo_password]
+
+Examples:
+  # Local install/update
+  sudo ./netbird-install-update.sh
+
+  # Deploy to a single host via SSH
+  ./netbird-install-update.sh --ssh user@hostname
+
+  # Deploy to multiple hosts from a file
+  ./netbird-install-update.sh --hosts-file hosts.txt
+
+  # Deploy with auto-update timer
+  ./netbird-install-update.sh --ssh user@hostname --timer --time "weekly"
+
+  # Multi-host deployment with default sudo password
+  ./netbird-install-update.sh --hosts-file hosts.txt --password "mypass"
+EOF
+    exit 0
+}
+
 while [[ $# -gt 0 ]]; do
     case "$1" in
+        -h|--help)
+            print_usage
+            ;;
         --ssh)
             SSH_HOST="$2"
             shift 2