Update README.md

[mstjern]

Removed Migration from V1 to V2

[macroscopeapp]

Remove the V1-to-V2 migration section from README.md to update documentation per “Update README.md”

Delete the migration content, including V1 WebSocket example, V2 SDK usage example, and the key differences table, so the page jumps from SDK usage to HTML5 Standalone in README.md

📍Where to Start

Start with the removed sections in README.md, focusing on the transition between the SDK usage snippet and the HTML5 Standalone Implementation section.

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Macroscope summarized 6a9f021.