[Stream] Document new Live Input enable/disable flag

[tsmith512]

Summary

Add info re new Live Input enabled prop

Screenshots (optional)

Documentation checklist

• Is there a changelog entry (guidelines)? If you don't add one for something awesome and new (however small) — how will our customers find out? Changelogs are automatically posted to RSS feeds, the Discord, and X.
• The change adheres to the documentation style guide.
• If a larger change - such as adding a new page- an issue has been opened in relation to any incorrect or out of date information that this PR fixes.
• Files which have changed name or location have been allocated redirects.

[github-actions]

This pull request requires reviews from CODEOWNERS as it changes files that match the following patterns:

Pattern	Owners
/src/content/changelog/	@cloudflare/pm-changelogs, @cloudflare/pcx-technical-writing
/src/content/docs/stream/	@tsmith512, @ToriLindsay, @cloudflare/pcx-technical-writing, @renandincer, @third774

[github-actions]

Preview URL: https://9f938f15.preview.developers.cloudflare.com
Preview Branch URL: https://tsmith-2026-02-live-input-disable.preview.developers.cloudflare.com

Files with changes (up to 15)

Original Link	Updated Link
https://developers.cloudflare.com/changelog/2026-02-24-disable-live-inputs/	https://tsmith-2026-02-live-input-disable.preview.developers.cloudflare.com/changelog/2026-02-24-disable-live-inputs/
https://developers.cloudflare.com/stream/stream-live/troubleshooting/	https://tsmith-2026-02-live-input-disable.preview.developers.cloudflare.com/stream/stream-live/troubleshooting/
https://developers.cloudflare.com/stream/stream-live/start-stream-live/	https://tsmith-2026-02-live-input-disable.preview.developers.cloudflare.com/stream/stream-live/start-stream-live/