Update rustdoc test

Author: GuillaumeGomez

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

@@ -1,6 +1,6 @@
 #![crate_name = "foo"]
 
-// The goal of this test is to answer that it won't be generated as a list because
+// The goal of this test is to ensure 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