d.rgb/manual: remove link to d.colors

              add simple usage example


git-svn-id: https://svn.osgeo.org/grass/grass/trunk@52737 15284696-431f-4ddb-bdfa-cd5b030d7da7

display/d.rgb/d.rgb.html

@@ -39,11 +39,15 @@ r.colors map=image.3 rast=image.1
 To write out the color composite to a R/G/B raster maps, use
 <em><a href="r.composite.html">r.composite</a></em>.
 
+<h2>EXAMPLE</h2>
+
+<div class="code"><pre>
+d.rgb red=image.1 green=image.2 blue=image.3
+</pre></div>
 
 <h2>SEE ALSO</h2>
 
 <em>
-<a href="d.colors.html">d.colors</a>,
 <a href="d.colortable.html">d.colortable</a>,
 <a href="d.his.html">d.his</a>,
 <a href="r.blend.html">r.blend</a>,