[DOC] Add class diagram

README.md

@@ -33,3 +33,8 @@ rqt
 In the rqt window, select the menu Plugins -> rqt plugins -> GPS Map View 
 
 Click on the refresh icon to make the data sources available. 
+
+## Design
+
+<img src="http://yuml.me/diagram/scruffy/class/[QWidget]^[GpsMapViewWidget], [GpsMapViewWidget]++0..n->[GnssMarker], [GpsMapView]->[GpsMapViewWidget],[GpsMapViewWidget]++0..n->[QCheckBox], [GnssMarker|-longitude:double;-latitude:double;timer:QTimer|track();getLongitude();getLatitude();], [QCheckBox]-.-[note: A chaque activation/désactivation, mets à jour la liste de GnssMarker]"/>
+