adding new parameter to nlp learner

[pedroschoen]

Instructions

• Follow the instructions in README.md
• Delete everything between parenthesis (...)
• Remove the sections that are not relevant

Status

READY
IN DEVELOPMENT
HOLD
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• IN DEVELOPMENT: there's active development being done in this branch, don't merge yet
• HOLD: development is done, but PR shouldn't be merged yet (e.g. a correspondent PR in another service needs to be merged first)
• READY: development over and everything ready for merging
  (leave only one of the options above)

Todo list

• Documentation
• Tests added and passed
• Issue: closes #xxxx (write the number of the GitHub issues that this PR resolves)

Background context

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Description of the changes proposed in the pull request

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Related PRs

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Where should the reviewer start?

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Remaining problems or questions

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