+Nikos's inversion trick (merge from devbr6)

git-svn-id: https://svn.osgeo.org/grass/grass/trunk@38666 15284696-431f-4ddb-bdfa-cd5b030d7da7

raster/r.colors/r.colors.html

@@ -217,6 +217,7 @@ nv white
 end
 </pre></div>
 
+
 <h2>EXAMPLES</h2>
 
 The below example shows how you can specify colors for a three category map,
@@ -244,7 +245,8 @@ r.colors map=threecats rules=rules.file
 </pre></div>
 
 <p><br>
-To create a natural looking LUT for true map layer <i>elevation</i>, use the
+To create a natural looking lookup table (LUT) for true map layer
+<i>elevation</i>, use the
 following rules specification file. It will assign light green shades to the
 lower elevations (first 20% of the LUT), and then darker greens (next 15%, and
 next 20%) and light browns (next 20%) for middle elevations, and darker browns
@@ -261,6 +263,12 @@ next 20%) and light browns (next 20%) for middle elevations, and darker browns
 100% 255:255:100
 </pre></div>
 
+<p><br>
+To invert the current rules: 
+<div class="code"><pre>
+r.colors current_raster -n rast=current_raster
+</pre></div>
+
 
 <h2>SEE ALSO</h2>