docs: mention that svelte:self can be in a slot (#6184)

Author: geoffrich

site/content/docs/02-template-syntax.md

@@ -1430,7 +1430,7 @@ Named slots can also expose values. The `let:` directive goes on the element wit
 
 The `<svelte:self>` element allows a component to include itself, recursively.
 
-It cannot appear at the top level of your markup; it must be inside an if or each block to prevent an infinite loop.
+It cannot appear at the top level of your markup; it must be inside an if or each block or passed to a component's slot to prevent an infinite loop.
 
 ```sv
 <script>