alphametics: remove puzzles that use operators other than addition
alphametics: remove puzzles that use operators other than addition

kgengler/x-common,exercism/x-common,jmluy/x-common,jmluy/x-common,rpottsoh/x-common,ErikSchierboom/x-common,ErikSchierboom/x-common,petertseng/x-common,kgengler/x-common,petertseng/x-common,exercism/x-common,Vankog/problem-specifications,rpottsoh/x-common,jmluy/x-common,Vankog/problem-specifications