r.series.interp.html: fix param name in example

git-svn-id: https://svn.osgeo.org/grass/grass/trunk@57917 15284696-431f-4ddb-bdfa-cd5b030d7da7

raster/r.series.interp/r.series.interp.html

@@ -26,7 +26,7 @@ r.mapcalc expr="prec_5 = 500"
 
 <div class="code"><pre>
 r.series.interp --v input=prec_1,prec_5 datapos=0.0,1.0 \
-                  output=prec_2,prec_3,prec_4 sampoint=0.25,0.5,0.75 \
+                  output=prec_2,prec_3,prec_4 samplingpos=0.25,0.5,0.75 \
                   method=linear
 </pre></div>