Update main illustration

grid_models.md

@@ -13,6 +13,8 @@ The gridded models are using the same "traffic light" color pattern for indicati
 
 <img src="illustrations/grid_models_01.png" alt="Grid models example" width="1024"/>
 
+*The screenshot shows how results from the Carrot Rust Fly temperature model are presented in VIPS. You select date using the slider in the lower left corner, and you select parameter using the radio buttons in the lower right corner. By clicking in the map, a popup shows the warning status and values of any other parameters.*
+
 ## Prerequisites
 * You should be familiar with web maps and WMS services
 * You should be familiar with using and manipulating gridded weatherdata files, e.g. NetCDF files or GRIB files.