documentation update

* satisfy compiler when warnigs are enabled
  e.g. lib.rs include #!(warn(missing_docs))

Signed-off-by: Ralf Zerres <ralf.zerres@networkx.de>

src/schema.rs

@@ -1,3 +1,5 @@
+#![allow(missing_docs)]
+
 table! {
     claims (id) {
         id -> Integer,