[rfc/testsuite/doco] deprecate.txt

[Michael Chastain]

> I won't fight you if you feel strongly about that, but let me ask:
> why do you think it is better to keep this file separate?  My
> experience tells me that having several separate files is worse than
> having a single file.

It's likely to grow and change rapidly for a couple of weeks,
so I want to keep it separate during that stage at least.

But it is doco, so you get to tell me how to organize it.

Michael