Well, based on the sample snippet, there's was a line break just before each date, right? You could try

perl -pi.bak -e 's/ *(?:\d{4}-\d{2}-\d{2})/\r\n/g' filename
[download]

That inserts CRLF before the date at all instances and saves the original to filename.bak - see perlrun.

update: Oops, typo. I mean

perl -pi.bak -e 's/ *(?=\d{4}-\d{2}-\d{2})/\r\n/g' filename
[download]

Thanks, johngg!

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