gnucash-docs master: Fix build error introduced in most recent merge

[Geert Janssens]

Updated	 via  https://github.com/Gnucash/gnucash-docs/commit/1723d8a2 (commit)
	from  https://github.com/Gnucash/gnucash-docs/commit/484dc57c (commit)



commit 1723d8a28a5c74694e7c7476eb151e08e3e8cf7c
Author: Geert Janssens <geert at kobaltwit.be>
Date:   Sun Aug 21 22:23:26 2022 +0200

    Fix build error introduced in most recent merge



Summary of changes:
 cmake/AddXdgHelpTarget.cmake | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)