Node.js Demo - Add Logo, HTML, and Signature Pad (#16)

* Node.js Demo - Add Logo, HTML, and Signature Pad

* Update surey and documentation

* Fix formatting in index.js

* Add links to HTML/SignaturePad

* Remove spaces

* Fix the image note

* Update readme

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Co-authored-by: Roman Tsukanov <roman.tsukanov@devexpress.com>