bracket-push: remove ambiguity in description
bracket-push: remove ambiguity in description

fixes #1178
Rewording now indicates that the input string `may` have instead of `will` have.  This revision is intended to also imply that the input string might not contain any valid pairs. 
rpottsoh/x-common,ErikSchierboom/x-common,petertseng/x-common,jmluy/x-common,exercism/x-common,rpottsoh/x-common,petertseng/x-common,ErikSchierboom/x-common,jmluy/x-common,jmluy/x-common,exercism/x-common