r.kappa manual: export Kappa matrix as CSV file

raster/r.kappa/r.kappa.html

@@ -70,6 +70,9 @@ Example for North Carolina sample dataset:
 <div class="code"><pre>
 g.region raster=landclass96 -p
 r.kappa -w classification=landuse96_28m reference=landclass96
+
+# export Kappa matrix as CSV file "kappa.csv"
+r.kappa classification=landuse96_28m reference=landclass96 output=kappa.csv -m -h
 </pre></div>
 <p>