Added danish to po4a.cfg to validate it during weblate pulls.

Author: petterreinholdtsen

docs/po4a.cfg

@@ -1,6 +1,6 @@
 [options] --master-charset UTF-8 --localized-charset UTF-8
 
-[po4a_langs] cs de es fr hu it ka nb pt_BR ru sk tr uk vi zh_CN
+[po4a_langs] cs da de es fr hu it ka nb pt_BR ru sk tr uk vi zh_CN
 [po4a_paths] po/documentation.pot $lang:po/$lang.po
 
 [po4a_alias:AsciiDoc_def] AsciiDoc opt:"--keep 0 --option 'entry=lang' --option 'tablecells'"