[tex-live] tl'12 -> pretest -> tl'13 timing

[Karl Berry]

FYI ... the test builds of the sources for TL'13 are going well enough.
I'm expecting to shut down TL'12 updates for good in about a week.
It'll take at least a few days after that to set up the pretest.
After that will be a goodly period of dealing with whatever bugs are
reported (I expect plenty) and updating the documentation.

I wrote some draft dates on the tug.org/texlive home page, but don't
take them seriously.  It'll take however long it takes, as always.

More announcements as the time comes.

karl