docs: add section explaining Types global namespace usage (#97)

[Adityapradh]

This PR adds a new documentation file types-global-namespace.md explaining how to use a global Types namespace in a TypeScript project using declaration: true and global.d.ts.

It also updates README_SOURCE.md and regenerates README.md accordingly.

Closes #97

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IssueHunt Summary

Referenced issues

This pull request has been submitted to:

• #97: Add a section about Types global namespace

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