Refactored the document, implemented todos in Polygon ID State Replic…

…ation tutorial (#16)

* very early version of the tutorial with contracts only

* refactored the contracts section

* Added the front-end part of the tutorial

* Corrected the changelog

* Corrected the suggested changes: refactored the document, code sections, links; added images that show the flow

* Added the code snippet of relayer usage

* Corrected the suggested changes

* minor fix

* Changed img alt text

* proofreading pt.1

* Added todos

* Improved structure

* refactored the document, implemented todos

* refactored user flow

* moved the document

* Corrected the suggested changes: refactored user flow a bit, added link for smart contracts repo

* small fix

* Proofreading

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Co-authored-by: Ihor Diachenko <ih.diachenko@gmail.com>