add --zeroconf help message

Author: Stefal

tools/install.sh

@@ -73,6 +73,10 @@ man_help(){
     echo '        -m | --detect-modem'
     echo '                         Detect LTE/4G usb modem'
     echo ''
+    echo '        -z | --zeroconf'
+    echo '                         Install zeroconf/avahi service definition.'
+    echo '                         It helps to detect the base station on the network.'
+    echo ''
     echo '        -s | --start-services'
     echo '                         Start services (rtkbase_web, str2str_tcp, gpsd, chrony)'
     echo ''