high-scores: Rename highest -> personalBest
high-scores: Rename highest -> personalBest

jmluy/x-common,petertseng/x-common,jmluy/x-common,petertseng/x-common,exercism/x-common,rpottsoh/x-common,ErikSchierboom/x-common,ErikSchierboom/x-common,exercism/x-common,jmluy/x-common,rpottsoh/x-common