refactor(cli): --config -> --rules

[cmdoret]

Proposed Changes

Rename the -c/--config flag to -r/--rules. The name is more specific and this would need to be done anyways when tackling #45.

Types of Changes

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apply

• A bug fix (non-breaking change which fixes an issue).
• A new feature (non-breaking change which adds functionality).
• A breaking change (fix or feature that would cause existing
  functionality to not work as expected).
• A non-productive update (documentation, tooling, etc. if none of the
  other choices apply).

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• I have read the
  CONTRIBUTING
  guidelines.
• I have added tests that prove my fix is effective or that my feature
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• I have added the necessary documentation (if appropriate).

Further Comments

[marftn]

LGTM :)