Migrate JavaScript API&SDK documentation to new structure - Task 1

[DevpriyaDave]

• I have read and followed the Contributing docs, especially the "First-time contributing?" section.
• This PR has content that I did not fully write myself.
  • I used AI and I have read and followed the Generative AI Contribution Policy.
• I have the experience and knowledge necessary to understand, review, and validate all content in this PR.¹

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This closes first task of issue #5690
Based on #4853 this PR changes the title from Getting Started to Getting Started By Example for js docs.

Footnotes

1. Yes, I can answer maintainer questions about the content of this PR, without using AI. ↩

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: DevpriyaDave / name: Devpriya Dave (e982b08, 0c87a37, eb3c4b8)

[theletterf]

@DevpriyaDave Could you sign the CLA?

[DevpriyaDave]

@DevpriyaDave Could you sign the CLA?

@theletterf I believe I already signed and it does show in this PR

The committers listed above are authorized under a signed CLA.
✅ login: DevpriyaDave / name: Devpriya Dave

let me know if I am missing something or there are any additional steps. Thank you for reviewing.

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