Document additional functionality clearly

[kmanwar89]

Currently, the keylogging, screenshot, download & upload functions, as well as the DDoS capabilities are not documented anywhere, and are only found by digging through the source code. I will submit a pull request when I can, but in the meantime it'd be great to fully document all the features of this awesome project.

Thanks for your work on this.

[sweetsoftware]

Hello kmanwar89,

Now every functionality is documented in README.md