category label set example added

git-svn-id: https://svn.osgeo.org/grass/grass/trunk@32890 15284696-431f-4ddb-bdfa-cd5b030d7da7

raster/r.category/r.category.html

@@ -153,6 +153,17 @@ values in the output.
 </pre></div>
 </dl>
 
+<dl>
+<dt>Example defining category labels:
+<dt><span class="code"><pre>
+r.category thresh_gt0_lst_${YEAR}${MONTH}_avg_filt cats=1 rules=- << EOF
+1:potential absence
+2:potential presence
+EOF
+</pre></span>
+<dd>
+sets the categoy values 1 and 2 to respective text labels.
+</dl>
 
 <h2>TODO</h2>