Markdown not properly grouping paragraphs under <details> tag in some cases

[kareila]

https://www.dreamwidth.org/support/see_request?id=46691

In the cases provided by the user in the linked support request, the one that behaves improperly is the one where multiple contained paragraphs are only indicated by line breaks. Sounds like the details tag gets autoclosed after the first paragraph unless it also uses p tags - at least when the entry is using Markdown mode.