add gestures to ubuntu code example

Example: gestures in ubuntu

##### Gestures in Ubuntu #####

## Steps to Install 
sudo gpasswd -a $USER input
sudo apt install libinput-tools xdotool

## make a text-file for saving your gestures like the same below...
nano .config/libinput-gestures.conf

## add all gestures below into that file
gesture swipe left 3 xdotool key alt+Right
gesture swipe right 3 xdotool key alt+Left
gesture swipe right 4 xdotool key ctrl+alt+Left
gesture swipe left 4 xdotool key ctrl+alt+Right
gesture swipe up 3 xdotool key super
gesture swipe down 3 xdotool key super+d

## After doing above steps type these commands in terminal and logout...
libinput-gestures-setup start 
libinput-gestures-setup autostart

### Enjoy you are done!!!