buf[3] to buf[7] are not reserved!

[MasterExecuson]

We can send multiple key presses at the same time utilizing the buf[3] to buf[7]! Please correct this in the documentation, I created a Pull Request with those changes!

The way it seams to work is that each the first declaration is sent first despite the buf[number]. This can be tricky in some Softwares, as, for example, F24 and control is different from control + F24.