RFD: Draft guidelines for working on jdk8u

[Langer, Christoph]

> I made a mistake. I meant to say
> 
> > Patches pushed to jdk8u-dev will be copied to jdk8u at regular intervals.
> > When the time comes for an update release,
> > jdk8u [not jdk8u-dev] will closed for testing and stabilization. From
> > that point onwards only critical bug fixes may be applied to jdk8u, at
> > the discretion of the maintainers.

OK, that's better �� Effectively, jdk8u will always be closed for testing and stabilization...

/Christoph