Docs: drop region codes

This should result in a translated documentation for locale settings like e.g. de_AT or it_CH, which before only got english docs.
You will need to rerun autogen to rebuild the makefiles.

BP  

git-svn-id: svn+ssh://svn.gnucash.org/repo/gnucash-docs/trunk@23523 57a11ea4-9604-0410-9ed3-97b8803252fd