Update crate attributes

src/lib.rs

@@ -1,6 +1,8 @@
 //! # pollard
 
-#![deny(intra_doc_link_resolution_failure)]
+#![cfg_attr(docsrs, feature(doc_cfg))]
+// Catch documentation errors caused by code changes.
+#![deny(broken_intra_doc_links)]
 #![deny(missing_debug_implementations)]
 #![deny(missing_docs)]
 #![deny(unsafe_code)]