Document the config.json `solution_pattern` key.
Document the config.json `solution_pattern` key.

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