Sync svelte docs (#1442)

sync svelte docs

Co-authored-by: svelte-docs-bot[bot] <196124396+svelte-docs-bot[bot]@users.noreply.github.com>

Author: github-actions[bot]

apps/svelte.dev/content/docs/svelte/98-reference/21-svelte-action.md

@@ -3,6 +3,8 @@ NOTE: do not edit this file, it is generated in apps/svelte.dev/scripts/sync-doc
 title: svelte/action
 ---
 
+This module provides types for [actions](use), which have been superseded by [attachments](@attach).
+
 ## Action
 
 Actions are functions that are called when an element is created.