minor text

git-svn-id: https://svn.osgeo.org/grass/grass/trunk@58405 15284696-431f-4ddb-bdfa-cd5b030d7da7

raster/r.topmodel/r.topmodel.html

@@ -130,7 +130,7 @@ the <b>outtopidxstats</b> file using the following command:
 <div class="code"><pre>
 r.stats -Anc input=[topidx] output=[outtopidxstats] nsteps=[ntopidxclasses]
 </pre></div>
-These three parameters can be omitted unless new topidxstats file needs to be
+These three parameters can be omitted unless a new topidxstats file needs to be
 created.
 </dd>
 </dl>