Correct inconsistency in sum of multiples readme
Correct inconsistency in sum of multiples readme

The exercise states that the multiples should not include the higher bound, but then the
example immediately after that includes the upper bound.

Fixes exercism/exercism.io#2579

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