Refactor Multitrack publish and play document

[yashtandon113]

Link to the documentation page or resource

https://antmedia.io/docs/guides/publish-live-stream/multitrack-publish-and-play-with-ams/

Describe the bug

Some users want to publish multiple streams without room and want to play them on a single stream.

For that, the new multitrack-play.html sample page can be used to play the main track, including the multiple streams as subtracks.

Additional context

No response

Suggested improvements or fixes

No response

Related issue(s)/PR(s)

No response