complex-numbers: add detailed description
complex-numbers: add detailed description

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