time package needs a tiny README file

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,