r.watershed: link r.stream.extract in the manual

             (merge https://trac.osgeo.org/grass/changeset/59921 from trunk)


git-svn-id: https://svn.osgeo.org/grass/grass/branches/releasebranch_7_0@59922 15284696-431f-4ddb-bdfa-cd5b030d7da7

raster/r.watershed/front/r.watershed.html

@@ -511,7 +511,8 @@ Food Production In Arid Zones</b> (Tucson, AZ, 12-16 Oct. 1987).
 <a href="r.resamp.interp.html">r.resamp.interp</a>,
 <a href="r.terraflow.html">r.terraflow</a>,
 <a href="r.topidx.html">r.topidx</a>,
-<a href="r.water.outlet.html">r.water.outlet</a>
+<a href="r.water.outlet.html">r.water.outlet</a>,
+<a href="r.stream.extract.html">r.stream.extract</a>
 </em>