fix compilation of doc (broken by changeset bc6d78982f

- General tightening/testing of vectorwise ops)

doc/examples/Tutorial_ReductionsVisitorsBroadcasting_broadcast_simple_rowwise.cpp

@@ -13,7 +13,7 @@ int main()
   v << 0,1,2,3;
        
   //add v to each row of m
-  mat.rowwise() += v;
+  mat.rowwise() += v.transpose();
   
   std::cout << "Broadcasting result: " << std::endl;
   std::cout << mat << std::endl;