atbash: fix typo s/exercim/exercism/ (#316)
atbash: fix typo s/exercim/exercism/ (#316)


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