Remove reference to nf33

[rbeucher]

Will close #7

[OKaluza]

The data dir is for files with take a long time to download and process, it is the same for all users so we can save a lot of space and time by providing a shared public location for the files. If nf33 isn't the place then that is fine but we don't want everyone to be hammering the NASA servers and having to reprocess all this data when running on gadi, it will be wasteful and make a big barrier to getting started that people will give up on.
For local users I intend to package up the processed files to github releases, so at least some of the download will be reduced and the processing step skipped but focusing on ARE users on gadi for now.

[rbeucher]

I agree. I put the files in xp65.