Add alternate text in readme

Signed-off-by: ClemensLinnhoff <[email protected]>

README.md

@@ -8,7 +8,8 @@ The "object based camera object model" is based on object lists and all modeling
 The outer layer of the model is the OSI Sensor Model Packaging (OSMP).
 It specifies ways in which models  using the Open Simulation Interface (OSI) are to be packaged for their use in simulation environments using FMI 2.0.
 For more detailed information see the official documentation.
-<img src="doc/img/OSMPCameraSensor_Demo.gif" width="800" />
+
+<img src="doc/img/OSMPCameraSensor_Demo.gif" alt="Camera Sensor Demo" width="800" />
 
 ## Modeling Approach