Fixed problem with doc test

src/iface/interface/mod.rs

@@ -342,7 +342,7 @@ let neighbor_cache = // ...
 # let ipv4_frag_cache = // ...
 # ReassemblyBuffer::new(vec![], BTreeMap::new());
 let ip_addrs = // ...
-# [];
+# heapless::Vec::<IpCidr, 5>::new();
 let builder = InterfaceBuilder::new()
         .hardware_addr(hw_addr.into())
         .neighbor_cache(neighbor_cache)