Fix dccp_available_ccids example

Author: Thomasdezeeuw

src/sys/unix.rs

@@ -2199,10 +2199,14 @@ impl crate::Socket {
     ///
     /// The API should be used in the follow way:
     ///
-    /// ```
+    /// ```no_run
+    /// # fn main() -> std::io::Result<()> {
+    /// use socket2::{Socket, Domain, Type, Protocol};
     /// let socket = Socket::new(Domain::IPV4, Type::DCCP, Some(Protocol::DCCP))?;
-    /// let (endpoints_array, len) = socket.dccp_available_ccids::<4>();
+    /// let (endpoints_array, len) = socket.dccp_available_ccids::<4>()?;
     /// let endpoints = &endpoints_array[..len];
+    /// # drop(endpoints);
+    /// # Ok(()) }
     /// ```
     ///
     /// [documentation]: https://www.kernel.org/doc/html/latest/networking/dccp.html