add comment about ISO 8601 and PHP 🙈
add comment about ISO 8601 and PHP 🙈

Signed-off-by: Morris Jobke <7f550a9f4c44173a37664d938f1355f0f92a47a7@morrisjobke.de>

pmattern/server,xx621998xx/server,pmattern/server,pixelipo/server,pmattern/server,Ardinis/server,nextcloud/server,whitekiba/server,Ardinis/server,michaelletzgus/nextcloud-server,michaelletzgus/nextcloud-server,Ardinis/server,whitekiba/server,nextcloud/server,pixelipo/server,andreas-p/nextcloud-server,andreas-p/nextcloud-server,andreas-p/nextcloud-server,pixelipo/server,endsguy/server,andreas-p/nextcloud-server,Ardinis/server,pixelipo/server,xx621998xx/server,pixelipo/server,Ardinis/server,whitekiba/server,michaelletzgus/nextcloud-server,endsguy/server,pmattern/server,endsguy/server,endsguy/server,michaelletzgus/nextcloud-server,xx621998xx/server,whitekiba/server,nextcloud/server,andreas-p/nextcloud-server,xx621998xx/server,xx621998xx/server,pmattern/server,nextcloud/server,whitekiba/server,endsguy/server