Roadmap visualization for learning Polkadot SDK

[chungquantin]

Build a visualization tool with this: https://roadmap.sh/roadmaps

Example of the roadmap for Blockchain Developer. We want a similar thing for Substrate developer
blockchain.pdf

This is super helpful because we can track the progress of the developers using this.

[chungquantin]

Link to the interactive roadmap: https://roadmap.sh/r?id=659a4664ae22c12523369370