[Target3001] Remove template

The `Target3001.gitignore` template hasn't been touched since it was added. I can't find any documentation on its files or any examples of git repositories which actually contain such files except one by the original submitter. I think that the tool is a bit too niche for this collection since even people who use it don't seem to use it with git. I'll keep this open for a while in case anyone objects.

/cc @mibe who introduced this in #198