Update documentation to reflect ignoring of unknown addresses

src/libstd/net/addr.rs

@@ -344,6 +344,9 @@ fn hash<H: hash::Hasher>(&self, s: &mut H) {
 /// some other type (e.g. a string) just for it to be converted back to
 /// `SocketAddr` in constructor methods is pointless.
 ///
+/// Addresses returned by the operating system that are not IP addresses are
+/// silently ignored.
+///
 /// Some examples:
 ///
 /// ```no_run

src/libstd/net/mod.rs

@@ -107,6 +107,9 @@ fn next(&mut self) -> Option<SocketAddr> { self.0.next() }
 /// This method may perform a DNS query to resolve `host` and may also inspect
 /// system configuration to resolve the specified hostname.
 ///
+/// The returned iterator will skip over any unknown addresses returned by the
+/// operating system.
+///
 /// # Examples
 ///
 /// ```no_run
@@ -116,7 +119,7 @@ fn next(&mut self) -> Option<SocketAddr> { self.0.next() }
 ///
 /// # fn foo() -> std::io::Result<()> {
 /// for host in try!(net::lookup_host("rust-lang.org")) {
-///     println!("found address: {}", try!(host));
+///     println!("found address: {}", host);
 /// }
 /// # Ok(())
 /// # }