Fix/update docs

[caboe]

Two changes to the docs:

• Add import fro GFetch, because imports are also available in the other code examples
• Add missing comma to the svelte.config.js, because otherwise this will create an error on start.

[height]

Link Height tasks by mentioning a task ID in the pull request title or commit messages, or description and comments with the keyword link (e.g. "Link T-123").

💡Tip: You can also use "Close T-X" to automatically close a task when the pull request is merged.