[racket-dev] Want to add an example to reference docs

I'd like to add something like the following example to the third
paragraph of section 1.1.16 on the implications on custodian shutdown:

    https://gist.github.com/4411396


Otherwise, without the example, it's easy to misinterpret the sentence:

    "If the current custodian is shut down before a procedure is
called to create a managed resource (e.g., open-input-port, thread),
the exn:fail:contract exception is raised."

to imply that closing a custodian with no associated resources to
raise an exception.


Alternatively, can we rephrase that sentence to the following?

    "Once the current custodian is shut down, if a procedure is called
that attempts to create a managed resource (e.g., open-input-port,
thread), then the exn:fail:contract is raised."



Thanks!