Delete ignored key from config.json
Delete ignored key from config.json

Since the exercise implementations are all in the exercises directory
we no longer need to ignore any non-exercise directories in the root
of the track.

mienaikage/exercism-perl6,mienaikage/xperl6,mienaikage/exercism-perl6,exercism/xperl6,mienaikage/xperl6,exercism/xperl6,mienaikage/exercism-perl6,exercism/xperl6,mienaikage/xperl6