Update readme.md

Author: nicolas-t

readme.md

@@ -4,12 +4,23 @@ Detects lightning strikes around you and beeps as the thunder approches :zap:
 
 ## Installation
 `git clone https://github.com/nicolas-t/petit-tonnerre.git`  
-`cd petit-tonnerre`.  
-`yarn install`. 
+`cd petit-tonnerre`  
+`yarn install` 
 
-## Configuration
-open `petit-tonnerre.js`,  
-update `myPosition` with your position's latitude and longitude.
+## Options
+you can list all options with `node petit-tonnerre.js --help`
+
+`--latitude` : the latitude of your position  
+`--longitude` : the longitude of your position  
+`--radius` : the maximum distance (in meters) around your position a strike will be detected  
+`--speed` : the speed of the sound (in meters per second)  
+
+## Examples
+__if you're in Hono Lulu:__   
+`node petit-tonnerre.js --latitude=21.3069440 --longitude=-157.8583330`    
+
+__with all options:__  
+`node petit-tonnerre.js --latitude=21.3069440 --longitude=-157.8583330 --radius=8000 --speed=342`  
 
 ## Usage
 run `node petit-tonnerre.js` from the `petit-tonnerre` folder.