Remove support for exercises in the root dir

[kytrinyx]

All the tracks now have moved their exercises into the exercises/ subdirectory.

TODO

• [x] Update Trackler - done https://github.com/exercism/trackler/pull/44
• [x] Update Configlet to only check the exercises subdirectory and not worry about ignored directories
  • https://github.com/exercism/configlet/pull/17
• [x] Release new configlet
• [x] Update https://github.com/exercism/request-new-language-track to remove "ignored" from config.json
  • https://github.com/exercism/request-new-language-track/pull/30
• [x] Write script and update all the tracks to remove "ignored" from config.json
  • https://github.com/exercism/meta/pull/7
• [x] Update config.json documentation
  • https://github.com/exercism/docs/issues/12
  • https://github.com/exercism/x-common/blob/master/CONTRIBUTING.md#track-configuration-file
  • https://github.com/exercism/request-new-language-track/blob/master/CHECKLIST.md
  • https://github.com/exercism/docs/blob/master/contributing-to-language-tracks/README.md

[Insti]

[todo list moved to original issue for tracking -kytrinyx]

[kytrinyx]

I've added a PR to configlet to stop supporting exercises in the root dir.

[kytrinyx]

The new configlet is released. I ran the script against the Chapel track (https://github.com/exercism/xchapel/pull/7), and it passes the build.