So Windows knows that LibO is able to open these files formats too.
The option will appear in the "Open With" menu.

Change-Id: Ifb4c4ec975ea5c84b1f18191d74fee0c39684f66
Reviewed-on: https://gerrit.libreoffice.org/5367Reviewed-by: Tor Lillqvist <tml@iki.fi>
Tested-by: Tor Lillqvist <tml@iki.fi>