After months of work by supporters, an ordinance that would decriminalize possession of small amounts of cannabis will be up to Denton voters when they head to the polls for the November city election. Two groups, Ground Game Texas and Decriminalize Denton, gathered nearly 3,000 signatures on a petition in support of the move in May. But before the ordinance could get on the ballot, the City Council had to approve it, which it did unanimously Tuesday.…