Update c++.cpp

for just the comments for the beginners

c/c++.cpp

@@ -4,6 +4,6 @@ using namespace std;
 
 int main()
 {
-   cout << "Hello World" << endl; 
-   return 0;
+   cout << "Hello World" << endl;  //print Hello Word on the screen 
+   return 0; // for convention
 }