gitignore globs are not repo-global by default.
They are so only with an explicit `/` in front.
Also, all files below an ignored directory
are ignored as well.
see http://kicad-pcb.org/help/file-formats/
> fp-info-cache: *: Footprint info cache:
cache of information (description, datasheet URL, etc.)
for all footprints used by the board.
