Add test for block doc comments

Author: GuillaumeGomez

src/test/rustdoc/strip-block-doc-comments-stars.docblock.html

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

src/test/rustdoc/strip-block-doc-comments-stars.rs

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+#![crate_name = "foo"]
+
+// The goal of this test is to answer that it won't be generated as a list because
+// block doc comments can have their lines starting with a star.
+
+// @has foo/fn.foo.html
+// @snapshot docblock - '//*[@class="rustdoc-toggle top-doc"]//*[@class="docblock"]'
+/**
+ *     a
+ */
+pub fn foo() {}