gnucash-docs maint: Fix license file

[Geert Janssens]

Updated	 via  https://github.com/Gnucash/gnucash-docs/commit/dd990803 (commit)
	from  https://github.com/Gnucash/gnucash-docs/commit/2cdba471 (commit)



commit dd990803695a0925b6263cb00620df93b92694ae
Author: Geert Janssens <geert at kobaltwit.be>
Date:   Wed Sep 22 20:53:04 2021 +0200

    Fix license file
    
    Use actual file instead of softlink.



Summary of changes:
 COPYING | 675 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 674 insertions(+), 1 deletion(-)
 mode change 120000 => 100644 COPYING