sync svelte docs

Author: svelte-docs-bot[bot]

apps/svelte.dev/content/docs/svelte/03-template-syntax/09-@attach.md

@@ -161,3 +161,7 @@ function foo(+++getBar+++) {
 ## Creating attachments programmatically
 
 To add attachments to an object that will be spread onto a component or element, use [`createAttachmentKey`](svelte-attachments#createAttachmentKey).
+
+## Converting actions to attachments
+
+If you're using a library that only provides actions, you can convert them to attachments with [`fromAction`](svelte-attachments#fromAction), allowing you to (for example) use them with components.

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

@@ -7,7 +7,7 @@ title: svelte/attachments
 
 ```js
 // @noErrors
-import { createAttachmentKey } from 'svelte/attachments';
+import { createAttachmentKey, fromAction } from 'svelte/attachments';
 ```
 
 ## createAttachmentKey
@@ -48,6 +48,52 @@ function createAttachmentKey(): symbol;
 
 
 
+## fromAction
+
+Converts an [action](/docs/svelte/use) into an [attachment](/docs/svelte/@attach) keeping the same behavior.
+It's useful if you want to start using attachments on components but you have actions provided by a library.
+
+Note that the second argument, if provided, must be a function that _returns_ the argument to the
+action function, not the argument itself.
+
+```svelte
+<!-- with an action -->
+<div use:foo={bar}>...</div>
+
+<!-- with an attachment -->
+<div {@attach fromAction(foo, () => bar)}>...</div>
+```
+
+<div class="ts-block">
+
+```dts
+function fromAction<
+	E extends EventTarget,
+	T extends unknown
+>(
+	action:
+		| Action<E, T>
+		| ((element: E, arg: T) => void | ActionReturn<T>),
+	fn: () => T
+): Attachment<E>;
+```
+
+</div>
+
+<div class="ts-block">
+
+```dts
+function fromAction<E extends EventTarget>(
+	action:
+		| Action<E, void>
+		| ((element: E) => void | ActionReturn<void>)
+): Attachment<E>;
+```
+
+</div>
+
+
+
 ## Attachment
 
 An [attachment](/docs/svelte/@attach) is a function that runs when an element is mounted