add instructions

README.md

 # Pnria Projet Deeplever
 
-## Requirements 
+## How to use it 
+
+Set the parameters and upload the models.
+The instance should either be a .txt at format (feature1=...,feature2=...) or a json file
+
+You will find possible models in the tests file
+
+## Trying the app
+
+### Requirements 
 
 `pip install -r requirements.txt`
 
-## Running
+### Running
 
 Run app.py then visit localhost