docs: Update text in Module 17 Sharing code

[pedroldk]

The goal of this PR is to make it clear that a new script block should be added instead of manipulating the current one.

---

HEADS UP: BIG RESTRUCTURING UNDERWAY

The Svelte repo is currently in the process of heavy restructuring for Svelte 4. After that, work on Svelte 5 will likely change a lot on the compiler aswell. For that reason, please don't open PRs that are large in scope, touch more than a couple of files etc. In other words, bug fixes are fine, but feature PRs will likely not be merged.

Before submitting the PR, please make sure you do the following

• [ x ] It's really useful if your PR references an issue where it is discussed ahead of time. In many cases, features are absent for a reason. For large changes, please create an RFC: https://github.com/sveltejs/rfcs
• [ x ] Prefix your PR title with feat:, fix:, chore:, or docs:.
• [ x ] This message body should clearly illustrate what problems it solves.
• [ x ] Ideally, include a test that fails without this PR but passes with it.

Tests

• [ x ] Run the tests with npm test and lint the project with npm run lint

[vercel[bot]]

@pedroldk is attempting to deploy a commit to the Svelte Team on Vercel.

A member of the Team first needs to authorize it.

[benmccann]

This tutorial is moving: https://learn.svelte.dev/tutorial/sharing-code

Any PRs are probably better sent to the new location: https://github.com/sveltejs/learn.svelte.dev/tree/main/content/tutorial/02-advanced-svelte/10-module-context/01-sharing-code

[pedroldk]

@benmccann https://github.com/sveltejs/learn.svelte.dev/pull/401 PR created in the new location. Should I close this one?