Fix the docstring.

git-svn-id: https://svn.osgeo.org/grass/grass/trunk@56689 15284696-431f-4ddb-bdfa-cd5b030d7da7

lib/python/pygrass/vector/__init__.py

@@ -385,7 +385,7 @@ class VectorTopo(Vector):
 
     @must_be_open
     def cat(self, cat_id):
-        """Return a list of geometry features with category == cat_id.
+        """Return the geometry features with category == cat_id.
         """
         return self.read(libvect.Vect_get_line_cat(self.c_mapinfo,
                                                    cat_id, self.layer))