sites -> points; explain -z flag. Missing power= from GRASS 6

git-svn-id: https://svn.osgeo.org/grass/grass/trunk@36582 15284696-431f-4ddb-bdfa-cd5b030d7da7

vector/v.surf.idw/v.surf.idw.html

@@ -21,30 +21,35 @@ rather than a raster map layer, as input.</p>
 <H2>NOTES</H2>
 
 <p>
-The amount of memory used by this program is related to the
-number of sites in the current region.  If the vector point map is 
+The amount of memory used by this program is related to the number
+of vector points in the current region.  If the vector point map is 
 very dense (i.e., contains many data points), the program may
 not be able to get all the memory it needs from the
 system.  The time required to execute is related to the 
 resolution of the current region, after an initial delay 
-determined by the time taken to read the input sites file.<p>
+determined by the time taken to read the input vector points map.</p>
+
+<p>
+To read and interpolate from the elevation co-ordinates as 3rd dimension
+of the vector geometry, use the <em>-z</em> flag. In this case no <em>column</em>
+parameter has to be specified.</p>
 
 <P>
 If the user has a mask set, then interpolation is only done
 for those cells that fall within the mask. However, all
-sites in the current region are used even
-if they fall outside the mask. Sites outside the current
+vector points in the current region are used even
+if they fall outside the mask. Vector points outside the current
 region are not used in the interpolation. A larger region may
 be set and a mask used to limit interpolation to a smaller area
-if it is desired to use sites from outside the region in the
+if it is desired to use vector points from outside the region in the
 interpolation. The <em>-n</em> flag may also be used to
 achieve a similar result.</p>
 
 <p>
-If more than <EM>count</EM> sites fall into one target raster cell, 
+If more than <EM>count</EM> points fall into one target raster cell, 
 the mean of all the site values will determine the cell value (unless
 the -n flag is specifed, in which case only the <EM>count</EM> 
-sites closest to the centre of the cell will be interpolated).</p>
+points closest to the centre of the cell will be interpolated).</p>
 
 <P>
 By setting <EM>npoints=1</EM>, the module can be used