Add type to connect_timeout

References #971

doc/sphinx/reference/vcl.rst

@@ -232,7 +232,7 @@ random or round-robin director or using .list::
           .list = {
                   .host_header = "www.example.com";
                   .port = "80";
-                  .connect_timeout = 0.4;
+                  .connect_timeout = 0.4s;
                   "192.168.15.0"/24;
                   "192.168.16.128"/25;
           }