DETROIT — Federal prosecutors alleged in a court filing Tuesday that a campaign employee of former President Donald Trump “encouraged rioting” to obstruct the counting of votes in Detroit after the November 2020 election. The revelation drew a direct connection between the frenzy that took place at Detroit’s riverfront convention center the day after the Nov. 3, 2020, election and the Trump campaign, which later trumpeted unproven and false theories of voter fraud in Michigan’s largest city. The new allegation came in a nine-page notice about evidence special counsel Jack Smith plans to introd…