Add internationalization steps in documentation

[GledsonAfonso]

Subject of the issue

Since there's a correlation between get-alex/alex, words/cuss and retextjs/retext-equality, we need some help updating the contributing.md file adding internationalization steps.

As mentioned in #202, the follow steps need to be specified on the file:

• The words and their respective rates need to be added to the words/cuss project, which will be used by the get-alex/alex project to detect profane words;

• The insensitive phrases need to be added to the retext-equality project, together with it suggested alternatives.

• Some important things to keep in mind:

  • On retext-equality project, the phrases are added by hand;

  • Only phrases in retext-equality have alternative suggestions.

[OtacilioN]

Hey @GledsonAfonso are you already writing this information in the guide? Or are you opening this issue to the community make it?

[GledsonAfonso]

It's open for the community, @OtacilioN, you can take it if you want. I opened the issue because I probably will not have the time to do it this weekend.

[Murderlon]

Agreed. Thanks to Hacktoberfest there have been lots of internationalization additions and discussions and this could help to keep that up 👍