Add cross-platform build script commands to README

[Hamza1610]

Description

This PR updates the Local Testing and Usage section in README.md to document the build script commands for all supported operating systems (Linux, macOS ARM, macOS Intel, and Windows).

Fixes #48

Notes to the reviewers

From the initil REAME.md only listed macOS ARM build command (generate-macos-arm64.sh) was mentioned, requiring developers on Linux, Windows, or Intel Macs to search through scripts/.

Changelog notice

• Documented Linux, macOS (ARM/Intel), and Windows build commands in README.md

Checklists

All Submissions:

• I've signed all my commits
• I followed the contribution guidelines

New Features:

• I've added docs for the new feature

[thunderbiscuit]

ACK 2976154.

Thanks for the work! One thing your commit is missing is a PGP signature. Can you add that? Otherwise this is ready to go!