time package needs a tiny README file

[Bryan O'Sullivan]

Hello, Ashley -

There's a bug open against ghc 6.6 regarding the time package, which 
notes that it doesn't install HsTime.h or HsTimeConfig.h when being 
installed.

If one already has a copy of the time darcs repo, it's still not obvious 
how to build it.  Please add a README with something like the following 
instructions, as a bit of Googling shows that I am not the first person 
to have spent a few minutes confused by this:

To build the time package, you must have GNU autoconf installed.  Run 
"autoreconf" before the usual Cabal build steps 
(configure/build/install).  There is no need to run the "configure" 
script; the Cabal build process will do this for you.

Thank you for your help,

	<b