docs(script): explain expected next/script behavior on client-side navigation

[balazsorban44]

This PR explains that a navigation via Link would not re-execute next/script components once they are added.

Fixes #42111

Ref: slack thread

Bug

• Related issues linked using fixes #number
• Integration tests added
• Errors have a helpful link attached, see contributing.md

Feature

• Implements an existing feature request or RFC. Make sure the feature request has been accepted for implementation before opening a PR.
• Related issues linked using fixes #number
• Integration tests added
• Documentation added
• Telemetry added. In case of a feature if it's used or not.
• Errors have a helpful link attached, see contributing.md

Documentation / Examples

• Make sure the linting passes by running pnpm build && pnpm lint
• The "examples guidelines" are followed from our contributing doc

[RemyMachado]

It tells the behavior, but doesn't explain how to re-execute the script on client-navigation...