d.rast.arrow manual: screenshot added

git-svn-id: https://svn.osgeo.org/grass/grass/trunk@69759 15284696-431f-4ddb-bdfa-cd5b030d7da7

display/d.rast.arrow/d.rast.arrow.html

@@ -73,6 +73,12 @@ r.mapcalc "direction = atan(U_map, V_map)"
 d.rast.arrow map=direction type=grass magnitude_map=magnitude skip=3 grid=none
 </pre></div>
 
+<!-- Data based on https://grasswiki.osgeo.org/wiki/GRIB -->
+<center>
+<img src="d_rast_arrow_wind.png"><br>
+<i>Sea wind speed (magnitude) and direction shown in the Tasmanian Sea</i>
+</center>
+
 <h2>SEE ALSO</h2>
 
 <em>