readme MD

README.md

@@ -13,6 +13,7 @@ its is currently developed by the **Remote Perception Group** in [**CentroGeo**]
 
 ## APISentinel
 This class makes easier the usage of [sentinel API](https://github.com/sentinelsat/sentinelsat).
+The class constructor requires a username and password form [copernicus project](https://scihub.copernicus.eu/dhus/#/self-registration)
 ### Dependencies
 ```bash
 sudo pip install sentinelsat