Fix #1: added script link and hotkey script

[MemoryOverclocked]

Feature

Now users can save their note by pressing alt+s.

How it works

1. Included script link from hotkeys.js library <script src="https://unpkg.com/hotkeys-js/dist/hotkeys.min.js"></script>
2. Included hotkey script which calls your function saveNote() when alt+s is pressed.

[PavanKKamra]

Hello Jack,

I have reviewed the pull request and I think this is a great functionality to add to my note taking application. I would like to thank you for contributing to my application. I will accept the changes.

Thank You,
Pavan K.