change name of force output file

main.cpp

@@ -51,7 +51,7 @@ int main(int argc, char** argv) {
         double meanForceMagnitude = sim.calculateMeanForceMagnitude();
         std::cout << "Mean force magnitude: " << meanForceMagnitude << std::endl;
 
-        sim.write2file(sim.getForces(), "../out/output.txt", 3);
+        sim.write2file(sim.getForces(), "../out/forces.txt", 3);
     } catch (std::exception& e) {
         std::cerr << e.what() << std::endl;
         return 1;