doc: imgs follow wiki:Submitting/Docs (better graphical index)

git-svn-id: https://svn.osgeo.org/grass/grass/trunk@72311 15284696-431f-4ddb-bdfa-cd5b030d7da7

imagery/i.cluster/i.cluster.html

@@ -18,7 +18,7 @@ initial number of clusters to be discriminated.
 
 <p>
 <center>
-<img src="landsat_cluster.png" border=1><br>
+<img src="i_cluster_landsat_clustering.png" border=1><br>
 <table border=0 width=590>
 <tr><td><center>
 <i>Fig.: Land use/land cover clustering of LANDSAT scene (simplified)</i>