Update references to CID draft to version 5
diff --git a/library/ssl_cli.c b/library/ssl_cli.c
index 110660e..f6d9048 100644
--- a/library/ssl_cli.c
+++ b/library/ssl_cli.c
@@ -444,7 +444,7 @@
 
     /*
      * Quoting
-     * https://tools.ietf.org/html/draft-ietf-tls-dtls-connection-id-04:
+     * https://tools.ietf.org/html/draft-ietf-tls-dtls-connection-id-05:
      *
      *   struct {
      *      opaque cid<0..2^8-1>;