site: docs: {@html} clarifications

This commit clarifies that `{@html}` directives cannot be used to surround markup with additional tags.
Also corrected the grammar in the descriptive text to remove dangling fragment.

Fixes #3456

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

@@ -318,10 +318,12 @@ If you don't care about the pending state, you can also omit the initial block.
 
 ---
 
-In a text expression, characters like `<` and `>` are escaped. With HTML expressions, they're not.
+In a text expression, characters like `<` and `>` are escaped; however, with HTML expressions, they're not.
 
 > Svelte does not sanitize expressions before injecting HTML. If the data comes from an untrusted source, you must sanitize it, or you are exposing your users to an XSS vulnerability.
 
+> Due to the limitations of the DOM APIs available to insert raw HTML fragments, this directive cannot be used to surround content with additional markup.
+
 ```html
 <div class="blog-post">
 	<h1>{post.title}</h1>