r.grow.distance manual: mention Geodesic metric

git-svn-id: https://svn.osgeo.org/grass/grass/trunk@58833 15284696-431f-4ddb-bdfa-cd5b030d7da7

raster/r.grow.distance/r.grow.distance.html

@@ -5,10 +5,10 @@ distance to the nearest non-null cell in the input map and/or the
 value of the nearest non-null cell.
 
 <h2>NOTES</h2>
-The user has the option of specifying four different metrics which
+The user has the option of specifying five different metrics which
 control the geometry in which grown cells are created, (controlled by
 the <b>metric</b> parameter): <i>Euclidean</i>, <i>Squared</i>,
-<i>Manhattan</i>, and <i>Maximum</i>.
+<i>Manhattan</i>, <i>Maximum</i>, and <i>Geodesic</i>.
 
 <p>
 The <i>Euclidean distance</i> or <i>Euclidean metric</i> is the "ordinary" distance