Add newlines around scribunto-doc-page-show wikitext

Change I15c10379 wrapped the scribunto-doc-page-show message in a div,
which is breaking things when the content of that message starts with
start-of-line-sensitive wikitext. So add a newline inside the div.

Bug: 60664
Change-Id: If596bed72f779f5980348ac111b63e7876d21ff4