docs: Add some services to Plugins and Utils page

[terrierscript]

I append some i18next friendly translation services ( i18nexus / localazy / crowdin).

Checklist

• [ ] only relevant code is changed (make a diff before you submit the PR)
• [ ] run tests npm run test
• [ ] tests are included
• [x] documentation is changed or added

[jamuhl]

changed that paragraph to make it clear it only shows services related to i18next (sponsoring or contribution)