Remove redundancy from the description of isogram
Remove redundancy from the description of isogram

When the blurb from the metadata of isogram:

> Determine if a word or phrase is an isogram

is combined with the description text, the resulting exercise
description becomes redundant.

> Determine if a word or phrase is an isogram. Determine if a word or
> sentence is an isogram. An isogram ...

So, this commit removes the redundant part from `description.md`.

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