Update mixed doc comments test

Author: GuillaumeGomez

src/test/rustdoc/mixing-doc-comments-and-attrs.S3_top-doc.html

@@ -0,0 +1,3 @@
+<div class="docblock"><p>Par 1</p>
+<p>Par 2</p>
+</div>

src/test/rustdoc/mixing-doc-comments-and-attrs.rs

@@ -16,3 +16,10 @@ pub struct S1;
 #[doc = "Goodbye!"]
 /// Hello again!
 pub struct S2;
+
+// @has 'foo/struct.S3.html'
+// @snapshot S3_top-doc - '//details[@class="rustdoc-toggle top-doc"]/div[@class="docblock"]'
+/** Par 1
+*/ ///
+/// Par 2
+pub struct S3;