fix script

src/pages/how-to/installation.mdx

@@ -183,20 +183,21 @@ curl -fsSL https://pkgs.netbird.io/install.sh | sh
 ```
 
 For NetBird to work on Synology after a reboot, you need to run this script every time you reboot your NAS. To automate this process, you can create a scheduled task in the Synology DSM.
-```bash
+
+```sh
 #!/bin/sh
 
 # Create the necessary file structure for /dev/net/tun
-if ( [ ! -c /dev/net/tun ] ); then
-  if ( [ ! -d /dev/net ] ); then
+if [ ! -c /dev/net/tun ]; then
+  if [ ! -d /dev/net ]; then
     mkdir -m 755 /dev/net
   fi
   mknod /dev/net/tun c 10 200
   chmod 0755 /dev/net/tun
 fi
 
 # Load the tun module if not already loaded
-if ( !(lsmod | grep -q "^tun\s") ); then
+if !(lsmod | grep -q "^tun\s"); then
   insmod /lib/modules/tun.ko
 fi
 ```